IIRC the rails on the MOE are aluminum, not polymer.
The January SHOT show debuts new products from makers, Magpul has at best hinted a mid-length MOE could, or could not be shown. Its's just a few weeks, I'll wait.
Instructors at carbine classes are quite fond of having students remove broken or useless rail attachments during the course. I'd study up closely from grads of the one selected to see if anything at all is recommended.
As for long term use, the continuing miniaturization of optics and lights will make a 4 rail obsolete in the future. They simply won't take up the space and make multiple rails necessary. I'm avoiding them.