Depends on the speaker. Morels are relatively shallow and are some of the best speakers available. The old DEI 3065s were great at the price, and Exile XPs are very good for the money. Illusion was great until they moved production overseas (they now appear to be defunct). Dynaudios are relatively shallow and are outstanding.
On the other hand, Blaupunkt also makes shallow-mount components...
It really depends on execution.