I may be wrong so please correct me if so... but if you shorten the top bushing, doesn't that just limit how deep you can turn?
So even if your trucks are looser, you can't lean as deep into the turn before it stops and thus your overall turning radius is worsen now despite the truck being looser.
I didn't test it very thoroughly and I also have flat tops on my ventures so not a 1 to 1 comparison, but standing on two of my friends' boards for like 30 seconds each (both of whom had the green loose conversion kits in their ventures), their seemed looser but didn't necessarily seem to have a deeper or sharper than mine
A small part of why aces have such a deep turn is because they have a pretty tall top bushing right? I put some venture stock tops in my aces once for shits and the shorter top made the turn max out much quicker.
Plus ventures already are relatively limited in the turning department, wouldn't it have made more sense to just provide a softer set of bushings that are the same dimensions?
Sounds like these make sense for those who want a looser feeling truck for small adjustments, but aren't necessarily good for somebody who finds the turn on venture limiting and wants a sharper turn
I have used a low top bushing for a long time, originally cutting down bushings back when there were no other options, then using the Indy bushing kit with the low heads. I still cut down a lot of bushings for people - some very light adults but mostly for kids - who just cannot turn with the bushings at the height and the kingpin on where it needs to be.
Yes full metal cupped washers will dig into the hanger and limit turn, but the washers that come with these are minimal in how much they cup the bushings, so I don't get any contact on the majority of them, and only very small amounts of contact on some bushings that are so flattened that there is not much bushing left, but all of them still do what I need them to.
In that regard, it is not so much about how much turn I have, but how responsive they are, so these ones I use in 92 duro are a touch harder than others, so I can have them loose feeling, but not wobbly, can lean a little left or right so they are still very responsive but they don't just go straight to wheelbite like other really soft bushings do. If I really put weight into it, all four wheels will touch the deck easily enough, but it takes a fair bit of effort right on that one wheel, so although I have significant wheelbite marks, I don't have issues with wheelbite from my usual setups.
Even on stock 90 duro cut down heads or the aftermarket 90 low heads, the responsiveness of the trucks is key, not how quickly they turn or how small the turning diameter is on flat ground.
To add after re reading, in response to some of your questions:
The only limiting factor in how deep a truck can turn is when the wheel stops on the deck, so for taller trucks / smaller wheels or trucks with thin risers, the turning circle can be very small, but on most setups with average size wheels and no risers, it is the wheelbite and not the bushings that will cause the issues.
Those flat washers are definitely a good one to give a much looser feeling on any bushings with any trucks. I tried it after I saw you guys do that and it is amazing how much of a difference it makes, with the kingpin nut in the same place. The Bones bushings flat washer is thicker than some I bought in a bulk washer pack a while back, but both work well in that situation too.
Ace turn I would say comes from the geometry of the trucks, cause even putting other brand bushings in them, they were still way more turny than these other trucks, no matter which bushing options were used.