You are right that 25 Vmax is a game changer, very happy my new 17H is a 9 twist so I can shoot them in it. Something about those 20s though, they just flat out shoot well in all my smaller 17s either 10s or 9 twists. When I first shot the factory loaded 20s from Hornady I was pleased with the accuracy but the velocity was a bit slower than their claimed velocity which I thought may have been due to the Rugers 18.5" choice of barrel length. I am happy to report that a fairly mild load of AA1680 in my handloads has achieved the factory spec of 3650fps with the 20 grain Vmax.
Thinking outside the box a little here I have always thought a 30 vmax for the larger 17s would be incredible, can you imagine the b.c. it would have and how well it would kill distant 'chucks or coyotes? I loved Todd's 30 Gold because it did exactly that, now that they are so scarce I feel Hornady could really do well with a new 30 grain bullet. The 25 Vmax is definitely a great bullet and fast in the bigger 17s but a new 30 could really be something special. Of course the bean counters would probably say just shoot a .204Ruger....
Matt