OK, my system is now built, and I rode in with it today. Sorry no pics or beamshots yet, but I'll post them eventually. Meanwhile, here's the lowdown:

- High beam: Philips Masterline 35W MR16, Optronics housing, mounted on front canti stud. $24, 150g.
- Low beam: Luxeon III MR16 (from autolumination.com), Optronics housing (housing drilled out in back to fit the bulb), mounted on front canti stud. $32, 140g.
- Front blinkie: Night-Sun/Lightman Xenon strobe, amber lens, on the handlebar. $40, 140g.
- Running lights: Pirahna 2-LED clearance lights, amber on front fork, red on rear seatstay. $15, 30g.
- Battery: pre-built 12V, 5000mAh NiMH pack (10 "C" cells) from batteryspace.com, fitted into a Zefal Magnum water bottle. 2 external connectors - one always "hot" for charging or high beam, one controlled by a waterproof switch mounted on the bottle cap, just like TurboCat sets them up. $60 (plus $30 charger), total weight 1050g including bottle, wiring, switch, fuse, etc.
- Connectors, switches, misc.: I utilized a number of parts from an old dead "donor" TurboCat system someone gave me. Bonus: TurboCat connectors mate perfectly with the connectors on the strobe, making it plug-n-play. By the way, the "pent" side of the connector is "+" and the "flat" side of the connector is "-".

Until now I have been riding with a 25-watt TurboCat S25 6V headlight system, which is just bright enough for my hilly, poorly lit suburban commute. The Macho SLA battery gives me plenty of runtime, but is also plenty heavy and bulky.

My objectives with this new system were:
- Water bottle battery. The placement of the TurboCat's huge brick makes it a major PITA to carry my bike up 4 flights of train station stairs in the morning. As it turned out, I needed the big Magnum bottle to hold the battery and associated wiring on top, but that's OK.
- Luxeon III based low beam. Low power consumption and still plenty of light for bike paths and moderate-speed offroading I occasionally do on the way home from work.
- Brighter high beam, with more total output and a broader beam than my current spots. And the new system ends up more than doubling the light output of the old one.
- No more weight than my existing system. The S25/Macho weighs 1550g. As it turned, out, the battery+headlight came in at about 1350g, plus 200g for the strobe and running lights. Nice!
- Moderate runtime on high beam. My evening commute is only about an hour, and I only need the high beam on 75% of it. Even assuming only 65% effectiveness due to cold temps and high current drain, 5000mAh should be enough for 45 minutes of high beam and plenty of leftover time on low beam+running lights. Or 6+ hours on low+running lights alone.
- Total cost under $200 for the battery+headlights. I hit that target easily, and the total cost for everything (including miscellaneous parts & supplies) was around $230.

So far I've only taken it out for a quick night ride around the 'hood, plus this morning's commute in broad daylight and a few minutes of demo'ing for curious coworkers. The real test will come in about a few hours. Here are my observations so far:
- Man, that 35W Philips bulb is bright! Even the 20W (spot beam) Philips is just as bright in the center as the full 25W of my TurboCat, but with a substantially broader beam. Impressive, since TurboCats are the best MR11-based systems out there besides Light & Motion. Just goes to show how much better off you are with a high-efficiency MR16. The 35W (narrow flood) is nearly as bright as the 20W Philips spot in the center, with an enormously broader beam. Definitely feels like we're in car-headlight territory. On last night's test ride, I kept looking back to see who was following me.
- The Luxeon III should be fine for low-beam use. This MR16-enclosed emitter is noticeably less bright than my Luxeon III Princeton Tec Apex headlamp, but still far brighter than their Luxeon 1W Eos headlamp. The Apex has much more sophisticated optics than the MR16, so no surprise here. In any event, it still throws quite a bit of light and should work fine for my low-beam purposes.
- The Luxeon III MR16 has a surprisingly well-focused beam, considering that it is specified as 100 degrees. The width of the hot spot is actually comparable the Philips 20W spot, and not much broader than the Apex. It's the spill that appears to go out to about 100 degrees, and while that area is proportionally a bit brighter than with other halogens, it's not excessive at all and there's still plenty of throw.
- The (automotive) LED clearance lights are amazingly bright too, enough to draw attention from any direction even in broad daylight. Well worth the 15g (!) of weight and 500mA of draw that each unit represents. I may put a second amber one on the other side of the fork. Maybe I'll also get myself a much smaller battery for summertime and commute with these babies year-round.
- I believe that the lumen output figures on the widely-quoted Starlight 78 Watts vs. Lumens page are flat-out wrong. I just don't think there is any way that an MR16 halogen is putting out 40+ lumens/Watt at rated voltage (or 50+ when over-voltaged), as claimed on that page I've looked at all the major light manufacturers' product lines, and there is hardly a halogen bulb in ANY format or of any size that puts out more than 15-20 lum/W. Check the Philips catalogue itself: their standard 20W MR16 only puts out 240 lumens, or 12 lum/W, and the super-efficient MasterLine (spot) I have puts out 370 (not 850), which is 18.5 lum/W. Even the 35W puts out 800 lumens, or 23 per watt. Many discussion threads on this board and elsewhere have cited these figures to show that Halogens are vastly more efficient than LEDs and just as efficient as HIDs. I've never been convinced, and the more I look the more it seems that the best Halogens are just as efficient as LEDs, and still not in the same league as HIDs. Don't get me wrong: it looks like my 880 lumen system will outshine many HIDs, but it also consumes an awful lot more juice and needs a much bigger battery.

All in all, thanks again to everyone who has contributed to the ENORMOUS amount of valuable information in this thread. Between this and the Starlight 78 page, I was able to make a huge number of "right" decisions that I might not have made otherwise.

- Dan