Have you ridden a rigid fork before? MRP makes good products so I'm sure that is fine fork but that is a lot of money to spend for a test. If this is your first time maybe look for a cheap used steel 29er fork like surly karate monkey fork. You would have to do some research but
CrMo MTB 29er/650b Fork | SOMA Fabrications
According to that a 80mm suspension corrected 29er fork will work for a 100mm 27.5 fork. Steel forks are generally pretty compliant while carbon ones very greatly.