Another option would be to use a PCIe SSD card instead of an M.2+PCIe. These are typically a striped RAID array of 2-4 discrete SSD controllers and NVRAM modules (plus some amount of DRAM cache) embedded onto a single card, all seen by the operating system as a single indivisible drive/controller.
The ROG RAIDR, Plextor M6e, and G.Skill Phoenix Blade all offer impressive Read/Write/Access (similar to SATA SSDs in striped RAID configurations). Some models are available with prices, capacities, and performances comparable to (or much better than) the Intel 750. And they don't occupy any PCIe 3.0 lanes or utilize a dedicated M.2 slot (which means they also don't lock out any other slots, ports, or other hardware resources on the motherboard). You could conceivably populate a motherboard with many such cards and move them from machine to machine with little difficulty.
These cards have been used in enterprise-class machinery for a while, and are now a "mature" storage technology which offers greater speed, reliability, longevity, and flexibility than consumer M.2 storage. I honestly don't know why M.2 is being pushed hard into the mainstream while PCIe SSDs are still seen as an oddball "niche" item (but I suspect most consumers think M.2 is the best new thing out there because they see every new motherboard proudly advertising M.2 compatibility).
Incidentally, a striped RAID of 2 or more good old SATA SSDs will offer similar (superior to most M.2) performance and price, in my opinion. It's hard to beat the price and performance of a striped pair of Samsung 850PRO SSDs, doubly so when their performance is multiplied through their RAM-caching software.
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