@Oopie: Yeah, I'm not quite done coloring yet; I want to get the middle resolved before I put any serious time into it.
@Agh

This is easily fixed by making that top exit accessible for all classes.

Here's what I see happening here:
RED: autogun w/ spamming engie
GREEN: spamming soldier or sniper
PURPLE: spamming heavy or any other bullet class.
RED: This is a very strong position, since it would be very hard to get in the blind spot without taking fire for a long time. However, a rocketman, sniper, or spy, standing on the far end of the platform, could take it out with relative ease.
GREEN: This guy shouldn't pose much of a threat, unless combined with the RED position. You've got two options to get to him, and the long reload times make him ineffective.
PURPLE: This a pretty strong defensive position, but it's similar to a heavy spamming behind a crate. A blue class standing on the platform might be hit him while outside of his range.
Worst case scenario: PURPLE and RED combined. I think you'd need an uber to get through that. The only fix I can see is adding a little tunnel behind the PURPLE guy, shown in grey. I don't really want to do this, however, because it really weakens Red's defensive options. That chokepoint is pretty much the only one they've got, and a rocketman or runner (light blue) gets around it pretty easily. Without it, I feel that games would suddenly turn into cap fests, and the slower classes would become useless.
Verdict: I'd really need to see a playtest to determine if it warrants fixing, but right now, I'm inclined to leave the way it is.
Thanks for the feedback, though!
Also, what if I removed the third floor in the v2 silo? That would create a better opportunity for a 'forward defense' but not turn it into a camp fest. Also, I was planning on shrinking the flat parts a little; I wanted to see if the concept was approved first.