Maybe it's just me, but i have never ever relied on a sales engineer for in-depth information on any car i buy. I get those from all over and more reliaby so. I use the sales person for sales related stuffs like availability of colors, trims, options, shipping dates, and the odd discount. What i do ask from them, is a pleasant and efficient sales experience and nothing more. For technical stuffs, i look to the SA or inhouse tech guru. No sense hammering the sales guy on technical stuffs just to prove that i know his job better.
This said dealership is indeed smaller than the photos would have u believe, but the service facilities are top notch! My M3 is a grey import, but my next M car will certainly be from them. The advantage of having a dedicated M dealership is that it allows the resources to be focused entirely on M related stuffs and not be swarmed by tons of regular BMW traffic. FOCUS is the key word!