The solution I've come up with, which is far from perfect, is to create a dummy gmail account, which is just for the calendar and contacts, to sync up with MfE, and then my regular gmail account is just IMAP on the N900. I only really need a single calendar so multiples is a non-issue for me.

FYI, the reason I chose to use a dummy gmail account is that I found having my regular gmail account (emails, contacts, caledar) as the MfE didn't sync the email properly, and having it as just contacts and calendar via MfE plus IMAP for email prevented for some inexplicable reason the signature from appearing when composing or replying to emails.

Off topic: the contacts sync fine but for several fixable bugs: no fax field on the N900 and because Google chooses to go with just one field for addresses instead of separate fields each for street, city, state and postal code, the addresses are a bit confusing with a # sign between each set of characters.