Perhaps it's a quibble, but points.com does not take a chunk of the miles as a transaction fee. Points.com finds the most efficient transfer path, which may involve unfavorable transfer ratios along the way. For example, let's say that Airline A transfers to Hotel B at 1:1 and Hotel B transfers to Airline C at 3:1. The Airline A to B ratio would be 3:1 but that's not going to points.com.

Likewise the transfer or trade fees on points.com are merely those charged by the loyalty programs themselves.

Points.com has its uses. During a promotion last year, I needed a lot of transfers into Aeroplan. Points.com could transfer 5 USAir points into 1 Aeroplan point. I made 24 such transfers, giving 120 USAir points for 24 AP points and getting a large bonus as a result.

Also, the ratio for AP to US is fairly favorable, last I looked it was 85% (hope it hasn't changed), thus giving a fairly good way to move Amex points into USAir.