APR makes less than REVO plain and simple, however when questioned about it, on the US forums etc, they openly say they could get morepower, but for longevity they choose to keep the power lower than what they could use.
REVO have the monopoly on the TFSI at the moment, so theres alot more of their software kicking about. but peak power isnt everything. Longevity and progressive maps and switchability also count for alot
I know of quite a few guys who have had REVO and gone elsewhere, or have had REVO on previous cars but will not go back to them for their next ones due to bad experiences. But saying that every tuner probably has the same.