Both series of those enclosed thespeakercompany inwalls are rebadged MB Quart Alexxas and Zurichs for 1/3 to 1/2 the price. They are an excellent value. As far as auditioning inwalls, as long as the inwalls you try second are physically larger than the first ones (and thus require a larger cutout) it won't matter that the first ones did not work out - just enlarge the hole to fit the 2nd ones. You will get at least two chances.
If the speakers are just for home theater, and he is willing to spend more, I would also advise you to check out the klipsch thx inwalls (7800 series and 7500 series).