I've played this map multiple times now on the No Heroes Payload server. I have some thoughts as to what can be done to improve it - as it is right now, I think the map has some big flaws.
The biggest problem with this map is that the second cap point is almost impossible to get with the right team mix/people. Teams were NOT stacked in any of these cases, so it's not as if the teams were badly imbalanced -- BLU has a lot of trouble trying to cap the 2nd point.
With the judicious placement of 3-4 sentry guns at the second point, both inside and maybe one outside guarding the rails, the point is next to impossible to cap. The main way up, through the long tunnel with the cart, is obviously pretty dangerous. I think the map maker's intention is for BLU to control the room through the two back stairwells, and then to push the cart up.
This is where the problem is -- with two or three sentries guarding the back door, I've seen BLU fail more times than not in capping this. Even with one or two ubers, the BLU team can probably take out the guns guarding the back, but not the one that inevitably remains in the front. With 3-4 active engineers building up a new set of sentries is very fast and easy, and there's more than enough metal in the room to achieve that.
I've also seen cases where a team successfully pushes the cart up the hill, but can't quite cap it. Then in the interim between them all dying and coming back up again, the sentries are all back up, and the cart inevitably rolls down the hill, and you're back to square one.
Also, if the RED team has any decent pyro, the ubers inevitably get blown off the back into the woods -- I've been in games where the entire back area was guarded by just two pyros and a gun, and it's more than enough to hold off a team of BLU players.
I think instead of tinkering with the last point, what needs to be fixed is so that the second point has a slightly more viable back way into the room. Right now, the second point almost always results in RED successfully defending it.