Lehghline, I am also a big fan of the PSX-ACs. I have one on each channel, between my PH-180s and the TIU. Possibly overkill in my case with the PH-180s, as those have also excellent electronic breakers! But, as you point out the PSXs are much cheaper than replacing the electronics in an engine! You can get 4 of them for less than having the electronics replaced in just a single engine.
Personally, I would definitely be using PSX-ACs if I was going to power my layout with old post war transformers. Phasing all transformers is also a very good point and important to do as well.
I also looked at street prices for a Z4000 and the PH-180s at Charles Ro. Z4000 = $459.95 ea. and PH-180 = $109.95 ea. (4 @ $439.80) so it's now pretty close to the same price between the two. The PH-180s still being a little less and offering more power. In case no one noticed, I am also a big fan of the PH-180s. 
Of course, the PH-180s are fixed output bricks and don't have handles, possibly a drawback to the plan here? So using the handles with the Fixed TIU Channels for conventional control would only apply to the Z4000 or other variable output transformers.
