I'm skating now almost a year back into it after 25 away. To summarize my experience with the new stiff skate boot offerings...
From 9060's to Super Tacks and a few in between, They all felt hard as a rock. ( Im 200lbs, not hockey agility fit but relatively fit)
I think the major problem for me with an ultra stiff boot was the heat molding and break in, wanting the boots to feel like part of my feet rather than an obstacle to overcome. Even after bakes and punches they always felt a bit "tippy" for me when going inside to outside or neutral to an edge. Abruptness/ un-smooth transitions across the edges because my ankles apparently aren't strong enough yet. Basically/probably relying on the boot for most of the support. I think this could have been avoided by starting with a flexible boot that I could lace up nice and snug where I feel supported but that still move "with" me, rather than an imperfect shell around my foot. Something with more natural/gradual deflection/bending that feels like more of an extension of what I'm trying to do out there. Perhaps a NS/NSX rec-level skate?
I'm not clanking around inside of my 9070's but there is that brief moment when doing certain things where I know the skate is gonna "tip" that tiny bit where it doesn't feel like part of my foot and I'm not in control at that time. Figure 8 kind of edge drills etc. I just started practicing 1 ft slaloms and they are truly frightening but doable. Things have gotten much better but it seems like I'm still not in sync w my skates.