Choosing a good 'flat panel' rear speaker

I am looking for speakers which are wall-mountable and to be used for rear surround purposes. My requirements are as follows:
- good sound quality; I will combine them with either Linn or B&W front speakers.
- reasonably full range; I know this is pretty impossible with shallow cabinets, but music is much more important to me than surround movie effects.
- shallow cabinet, preferably < 10cm;
- unobtrusive against white wall;
- in-wall speakers are not possible.

Currently I am looking at Linn Uniks (10cm depth), B&W SCM1 (18 cm depth) and Magnepan (3 cm depth, but 1m in height!).

Any advise would be very helpful!

Thanks.