Your brother is a bit off when he says "made by the lowest bidder"... The M4 is made by Colt to the M4 technical data packages which includes a lot of critical specifications. A factory new M4 or, as close as we can get it, the Colt LE6920 is a very good rifle when new. But as the rifles age and get round counts on them, parts maintenance and replacement must be kept up, just like any machine. This is often neglected (witness the numerous reports of soldiers getting issued beat to crap old magazines, rifles with worn ejectors and extractors, etc.
He does make a very good point- it's not just buying a rifle, it's buying rifles, spare parts, magazines (if the picked design does not use the M16/M4 mags) and lots of training and such.
The better interim solution is to be more proactive on maintenance and replacing worn out rifles and keeping up with training. The average soldier going into combat receives shockingly little weapons training, and the price for that has been paid in blood
Not to mention, the SCAR has it's issues from what I've heard that are still being worked out.
When it does come time for weapon replacement, it needs to be a full replacement including magazines, not an "improvement" of the AR platform (the SCAR is a lot of improvements in one rifle, for the most part).