Looks good to me although I have no experience with Merida. Sure 650b is the way to go. 140mm is great for Scotland and Wales, probably a lot more than you need riding locally but I run 140mm and travel a lot. You could probably get lighter and less travel if its to ride the Wolds exclusively. It really depends on your style of riding..
Hi there, im hoping to get out to Sherwood and other places a bit more having been there a few weeks back. My current merida 29er hardtail has been a decent bit of kit but if I'm honest I think the big wheels are hard work when things get more fun. Hopefully 650b is a good compromise.