Wingnut00,
I've been doing Ackley conversions for a couple of decades. Honestly, I don't care what increases I might achieve since I'm using the case because I like it and it allows me use a broader selection of powders. I test for the fastest, safe accuracy node and use it for that rifle. I don't have any percentages or facts that I can relate other than the fact that in the .25-06AI I get the performance I want when I hunt.
It is unfortunate though that the 1/4 bores have largely been ignored for the last 20 years or so. I've completed .25 BR, .25 Creedmoor, .25 Souper Improved, .257 Roberts AI, .250 Savage AI, .25-06 AI, .25 Gibbs, .257 Weatherby and .257 Condor (.25 cal. on the 7x61 S&H case). Of these I prefer to shoot the .250 Savage AI and the .25-06 AI.
Regards.