The ACHA should not be discussed in the same breath as the CIS and NCAA. The vast majority of the teams are nothing more than good men's league teams.
For the past two seasons, I have been out so skate with what is considered to be one of the better ACHA Div III teams here in the US. As a 38-year-old never-was, I could outskate about half the team. Sad, but true.
To put things in perspective, the best player on the the ACHA team I skate with played a total of 4 games of Junior A in Canada, in one of the lower-level Jr A leagues. In the ACHA Div III league, he is averaging about 3.5 PPG. He's a really nice kid, but he wouldn't even crack RMC's lineup.
The other comment that is noteworthy, and that I agree with, is Freddt's comment about the lack of games in Canada. Aside from UNB's home games, the only real evidence of any difference of playing in Canada vs. the US is the RMC-Army series.
If you look at the history of that series, between two low-end teams in their respective levels, you'll see that the games played in Kingston are always close (usually 3-2), whereas the ones played in West Point typically see Army enjoying 8-12 PP opportunities en route to a 4-5 goal win. Officiating plays a huge role, to say the least.
I would argue that, if you played home-and-home series between the top CIS and the top NCAA teams, you'd see a 50-50 split.
Of course, the NCAA has no interest in seeing that happen, because their sales pitch is that they present the best opportunity to develop while getting an education. Sending their best teams to Fredericton or Edmonton to be defeated would seriously undermine that message.