I would not get a rear-ported speaker or one with a passive driver (Forte) and put it that close to the wall in a main listening space. The Cornwall is obviously designed for that. You might want to consider something from the Heresy line before they added the rear port.
I have upgraded a couple of sets of speakers with Crites crossovers and honestly could not tell any difference. The Crites crossovers are designed to retain the sound of the stock crossovers. If a part in one of the original crossovers was bad it might be a worthwhile upgrade, otherwise I would spend money elsewhere.
Having said all that, you might call me a hypocrite, because I have a pair of Quartets in my bedroom that are placed just a few inches from the wall. I would not describe them as boomy, but I never turn them up very loud and the room has thick carpeting and my bed is right in front of them. They are there so that I can hear music while I'm getting ready for work in my adjacent bathroom, not for dedicated listening.
If you can find a pair of Epic series Klipsch CF1-4 speakers, those are front ported and IMHO sound better than the Legacy series. I had a pair of CF-3s and still somewhat regret selling them. There are three versions of the CF series, and the first version is regarded as the best by many. I had version 3 and thought those were fantastic.

