Question Building a surround system

[Gattous]

Dear all,
I am all new to this forum.

I am running the following in stereo mode:
* B&W 685 S2 on stands
* BK XLS200-FF (forward firing 10'')
* Sony STR-DN1050

I would like to upgrade this combination to a 5.1 surround setup.
For the center and after reading about matching issues, it looks like I should stay with the B&W HTM62. Due to space restricitons in my living room I would prefer not running an extra set of small bookshelfs like the B&W 686 S2 for example.
For the sole purpose of enjoying the surround effects in movies, would the satellite speaker B&W M1 do the job? Wouldn't it be overpowered by the strong fronts (685 S2 + HTM62)?
Do you have any suggestions for alternative satellite/surround speakers?

Thank you.

 

[PSM1]

Personally I would always want the same make and model of speaker all around but if space is a real issue then the M1s may be a reasonable compromise. Do not worry about them being overpowered since the amp will compensate for this but it can not compensate for any quality or tonal differences although these should be less noticeable in the surrounds.