Yeah the ones here are rectangular so you can't just flip them around! but they've started welding in cross-bars, so I guess that's a solution.
I always filter to the front and if traffic starts moving I'll basically move up to where my front wheel is right next to the rear wheel of the first car I get to that is also moving. Then if that car speeds up I get in behind them, or if they don't get moving I keep lane-splitting all the way up to the front if I can. I wouldn't recommend this for all commuters but I gotta get my deliveries in on time. If I can get all the way up to the front before the light changes I'll just get in front of all the cars and I'm usually off right as the light turns green and well ahead of traffic.

Also another safety concern I just thought about. Sometimes traffic is gridlocked for a couple of blocks, even though the lights are all green. When you're filtering up, as you get to the intersection, even though you have the green light, be careful. You may have the green light but pedestrians don't think of cyclists and WILL Jay-walk across the intersection. Theres a street here that backs up for 4 blocks all the time and peds are always blindly running across the intersection. Look out for them. Hell sometimes its not even one ped, it can be 20 at a time! So do be careful.

I'm continually amazed at the businessmen in the CBD who are there everyday and must be aware of the amount of cyclists and couriers who routinely jaywalk without looking. That some day-trippers aren't expecting a cyclist to come flying around the corner is one thing, but the amount of jaywalking businessmen who should know better astounds me. I ran into one the other day(He just decided to cross the road, the wave of cars had passed, and he didn't notice lil old me and I shoulder checked him pretty hard, "I guess you're not quite intelligent enough to be wearing such a nice suit eh?"
Seriously, how are people this stupid paid more than I am? But yeah, tourists and day trippers can't really be blamed but the businessmen who are in the CBD everyday should damn well know better.