Yes, this is exactly what I find. I think it's related to the cab block though. I notice when turning cab sims on/off (into a guitar cab) that, in addition to the obvious freq filtering, the attack curve seems to change. Like you say, feels like inserting a compressor.
The Motor Drive will cause compression if not set to zero (as it models driver compression). Otherwise the cab block is completely linear and will not cause any compression.
while the Axe has a safeguard built-in.
... my philosophy is, "one woman is enough to deal with... why would I want more?"