A map I'm working on, Thunderclash

So a while back I came up with an idea for a mode which combined the merits of CP and KotH maps and fixed a few of the problems I perceived with them. I sketched out several maps, and over Christmas I started building a map which would prove the mode in Hammer. It came together well across around two weeks in terms of structure and, to a certain degree, appearance. However, after Christmas my Harddrive failed and I lost all progress I had made on the map. I was playing less TF2 at that point and I really didn't feel like going in and starting over at that time. However, since getting back into TF2 for the Engineer Update, I've been thinking about the map and I've decided to give it another go.
So then, this mode was designed to resolve the problems with CP and KOTH that I perceived. In CP maps the problem is that too much of the time it devolved to a struggle over the middle 3 points where rarely will the attacking team manage to take the last point and win the game. Like in CP_BlackMesa, which I am quite fond of, the middle three points mearly change hands countless times across the course of 30 minutes. And while one team may be doing better, unless they manage to take that last point from the other they'll have nothing to prove it with. Meanwhile I think KoTH isn't dynamic enough. Basically, you're either trying to defend a single solitary spot or you're trying to take that single solitary spot and force them off it. There's a single set of entrances and exits and never an event where you say "I have to push forward now that I've done X." In KOTH, when you've done X, you've finished! Now all that's left is to sit down and see how long you can sit. 
Basically it works like this. Two countdowns are always counting down from say, 3 to 5 minutes. However, capture the middle point and you add 30 seconds to the other teams timer. Capture all 3 points, and only your timer ticks down. That's about it really. Simple, but I believe it rewards a team which manages to dominate their enemy consistently and encourages pushing for the team that's behind because if they do not push to the 3rd point they will lose.
I figure such a mode would have to have points which are easy enough to capture, but tricky to defend. That's the reasoning I have for the design of the central point I've done justice in Google Docs for this post. It's loosely based on the central point of CP_BlackMesa. The shade of the color indicates the height and the color sorta indicates material for some reason. Also, for what its worth, I'm currently going with a swamp motif for the map, with one side having a big laboratory and the other having the kind of wooden mansion you would expect to be haunted.

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I've changed up the design since 7 odd months ago mind, in a lot of little ways, but it has most of the same ideas. There probably should be more cover in a few places, and I've forgotten where I wanted the health and ammo, but still I like a lot about this design. 
The part I never really got down I think was the base, though it probably went through more design changes than the outside did. In theory, I believed that if the local team were to be expected to reclaim the control point, their spawns should be positioned on opposite ends of the base and have access to enough paths such that they could attack from anywhere to reclaim it. I was never able to figure out how exactly such a base should look, though I won't say I wasn't close. 
So that's basically it. I'm starting building it soon, but I'd really like to nail down the design of the map before I start this time and get the base right.  Also, I wanted to see what folk though of the design and the idea.