Please, for the sake of your sanity, avoid Pro8. Just do a search on pro8mm in the forum and you will see why.
I'm telling you Matt, if you ask to deal with Phil directly, things always go smoothly.
The trick is to actually get that to happen. Sadly, there just doesn't seem to be anyone else doing the "Max8"/"Super Duper 8" thing and it really does make a huge difference if you want 16x9 framing. Super 8 is grainy enough. Zooming into a 4x3 frame makes it almost unbearable, especially with 500T. Plus, even the most die-hard film fans will never give film more than a 300 lpmm resolving power. That number is very high. With a 6mm wide Super 8 frame, that's only 1800 lines. So, your 1920 is wasted. The more likely resolving power of 500T is probably 200-250 for possibly as low as 1200 lines. You're just resolving more grain at that point.
With an almost 7mm wide frame you are pushing 2100 and probably at least 1500 lines, making the 1920 more reasonable. It definitely looks WAY better.
Just widening the gate isn't enough with most cameras. At a wide angle the frame will vignette on all the Canon's. You really need to re-align the optics.
Anyway... just my 2 cents.