Bit more of an update.
I am defintely pedalling smoother with the spds on the mtb than with the flats. I always span well on the road bike, but didnt realise how choppy it was on the mtb until I changed.
Its easy to clip in and out, and on the couple of occasions where i have tested pedalling without clipping, its been ok, and would probably be even better with a skate/bmx style clipless shoe.
The M065 shoes i have are pretty comfy. Ordered a 45 as opposed to my normal 44 and they fit just right. The only niggle/s i have are:
The cleat can still be felt contacting the ground when walking, and feels as though it could be potentially dangerous on wet rock.
The top of the tongue digs into my ankle a bit. This couldbe solved by trimming it a little, but I am going to see if it softens up and digs in less.
All in all, pleased with my purchase, but will keep the flats just in case.