alvin's at vir right now, so you probably won't get a reply from him until monday.

i have a 905 cage on my bike. it's ok, but if i was buying a new one, i'd go with the powerz. especially for the street. looking at alvin's powers cage vs. my 905 cage, his cuts in farther at the lower edge of the cage, closest to the ground. meaning it's not so wide at that point. i've hit my cage in corners several times now, and it lifts the back tire off the ground every time. kinda scary, lol. looks like the powers cage would be less likely to do that.
the only reason i have a 905 is b/c it came as part of the deal with the bike.

i don't have any experience with the race rails, so i couldn't tell you much about them.