OK, got my hands on some stage 4 151s. Here's my pre-skate assessment:
Pretty much the same size as Ace AF1 60s, both having about a 153/ 154mm of hanger width.
The Indys are indeed taller and as we expected have less KP clearance.
They are also heavier. The AF1 60s I have came in at 406 grams (with just a little bit of wear) and the Indy 151s came in at 413 grams. Stage 11 159s are slightly wider and reportedly 402 gram, for comparison. So the Stage 4 reissue is certainly a heavy truck but again this was expected.
Next the Stage 4s bring the wheelbase in, even further than Ace. I haven't done the measurements but it looks pretty substantial.
Quality looks great. There is no way anyone is bending these fuckers. There is a tonne of meat under the hanger. The bushings feel like new Ace bushings. I'm sure they will firm up with use.
Based on what I am seeing so far, I bet they will turn as advertised but I might not get to actually skate them until Sunday so take all this with a grain of salt.
Edit* just went for a quick push around the block and holy shit these things turn fast... super quick and deep turn. Going to be very curious how they feel when actually skateboarding.