For the people asking if IMAP is worth it, if you are used to exchange, you will get troubled by the 15 minute delay in arrival and mails arriving in bunches.
I use a free google apps account and my exchange active sync is messed up ( it stops pushing at times) which is when I tried IMAP ( along with trying nuevasync, zohomail and what not). I am now archiving my 28000 mails and deleting it from the server to see, if it changes Exchange behaviour. If not, I will be purchasing mail2web's mobile email @ USD 5/mo and forwarding my google apps emails to get Activesync Push.
Fortunately, Active sync on my free google apps is still active. I have tried setting up a new iphone with my email ID and it works.