According to the re-print of Ackley's published improvements here:
Article posted on Precision Shooting Website about Ackley Improved cartridges - Shooters Forum
The .270 is listed twice. Most likely with different weight bullets. The velocity increases Ackley realized were listed as 7.8%-8.8% range.
Either one of those increases is pushing the .270WSM velocities.
I wouldn't mind getting 150gr SSTs or Interbonds (.525BC) up around 3100fps.
Plus, the case life and lack of case trimming would be worth it IMHO.
The .280AI has similar gains and it's popularity has skyrocketed in the last few years.