IMAP email hosting for small business: will "Google Apps" do?"

I've been tasked to revamp the current POP3 email hosting of a small business. Won't even bother going into the "POP vs IMAP" wrangle. Besides the obvious IMAP support, it's also pivotal that the service supports custom domain emails (ex: joe@mydomain.com). Taking into account the "small" in "small business", an affordable price point would also be nice.

It only took a couple minutes of research to bump into the Google Apps suggestion. Since it kept popping up over and over again, decided to take closer look into it. The free version allows one to create up to 50 accounts of 7 GB each. With full-fledged IMAP support and powered by Gmail's rock-solid backbone, Google Apps soon became the top contestant in the game. Notwithstanding, even though the overwhelming majority of reports classified the service as nothing short of first-rate, I did hear a significant clamor of warning shouts about the potential privacy concerns of hosting sensitive business information in Google's servers. The sometimes haphazard behavior when using mobile devices to access the service was also brought to my attention.

The quest for a more commercial solution returned dozens of potential candidates. After diligently analyzing each one, managed to prune the original list to four company's: FastMail, FuseMail, Rackspace and LuxSci. Although with slightly different bells and whistles, all four offer an equivalent set of core services. Even so, the several reviews I've come across categorically branded FastMail as the gold standard for "IMAP email hosting". There's no doubt in my mind that either one would get the job done. Unfortunately, every single price plan is way off-budget. I had no idea that commercial email hosting could be so expensive. At $63 user/year, in order to match the "50 accounts" figure provided by Google Apps, one would have to cough up $3150/year with Fastmail!! Even though with significantly less stratospheric prices, none of the other three will rival Google Apps offer for less than $1000/year.

I'm more than ready to go airborne with Google Apps. Nonetheless, before giving the green light, would like to hear your thoughts on the "privacy liability" topic. Would also appreciate some hands-on input on the "access from mobile devices is shabby" claims, as well as confirmation on "IMAP IDLE" support.

Thanks in advance!