What I've done so far: magpul AFG2, PA m3 red dot, Hogue grip & a few hundred rounds through it. Lots of fun for sure, almost forgot about my 5.56.....
That looks a lot like my setup. I do have ladder style rail covers now. I started with Magpul XTM but they made the rail feel really fat. I like a narrower feel so the ladders worked great.
That opens a whole 'nother can of worms. Once I removed my factory handguard, I went through a gas block, two front sights and four handguards before I came to my current setup with the VLTOR CASV-EL. I still have carbine and mid-length MOE handguard and an M4 handguard that I tried on it. Let him enjoy it how it is for a while before planting the seed of conversion in his mind.