To open the vega you have to twist off the reverse threaded lens cap, it might be a bit tight from the factory. I'm not too concerned with the seal on it as it hass an o-ring, I do plan on using some silicone grease on the ring and threads just for good measure. The batteries in it are 200mAh NiMH's there's a sticker on the battery pack that could provide more info but I didn't write it down and the light is down with my bike right now. Basically they're standard AA rechargables and I'm not worried about the new ones working.
I think that now with the intermittent disconnect taken care of the runtime won't be much different if not a little better. Would be interesting to be able to compare the bulb specs but haven't found the old one's around (or really looked). It does seem to put out some heat while on in my hand, but couldn't say that it is more than before.
I used a basic iron and it's not too hard to do, though a vice to hold the assembly helps as whenever soldering it seems like you need three hands. There are two metal strips (positive and negative, labeled on the boards as well) from the base control board to the LED star. The star is held onto the top mount by two small screws and the tabs in the star press fit onto two posts. A quick touch of heat to the solder on the star and you can push back the metal strips and free the board. I used a steel washer then to space the new one close to the old and solder the strip back together, keeping mind of the polarity. I'd say this is a pretty easy job if you have a soldering iron (or were looking for an excuse to get one). You'll need that, some solder, and if you wanted to be extra clean some solder wick to clean off the old stuff. Try not to leave a big blob at the end as the bulb head has to go around the star.
If you have an old light with a star board arrangement, this looks to be totally worth the couple of buck investment. Can't wait for it to get dark tonight.