There's no reason to trust Blackberry. Even though the new devices can do IMAP directly (not indirectly through the "cloud"), they send your login credentials to RIM.
Details: http://frank.geekheim.de/?p=2379
Details: http://frank.geekheim.de/?p=2379
As an aside, I checked out the new Q5 yesterday and it has refinements in all the right places. Both are highly underrated smartphones.