Really the only down side is the cost and the mags that are used...and a few complain it's to heavy.
Funny how people complain that it's heavy and others complain that there is too much "plastic". If they use less polymer then it would be even heavier and it they use more polymer then people think it's cheap. Can't win on this site.
The price of the mags is the most ignorant thing with these rifles. They are dirt cheap in the US but because they import only enough to maintain a high demand they can charge ridiculous amounts for these mags and the five cent rivet they put in them to make them Canadian legal. My Thermold mags were 100% reliable, so were my DSA mags though. Even my 5/30 DSA was perfect.
My gen 2 RFB was 100%reliable as long as you gave it enough gas to cycle. I had the occasional stoppage because I always ran mine with just barely enough gas for cycling to make it shoot super gentle. Accuracy on mine was about 1.5moa with handloads and 2-3moa depending what factory loads I put through it. I never tried any premium factory loads which probably would have been as good as my handloads.
The RFB is more than accurate enough to hunt any large game with and it is so compact that it's a pleasure to haul around all day through the bush.
Don't buy one if your one of the guys that thinks that just because a rifle is over $1500 it should be able to shoot Norinco ammo into tiny groups. The rifle was never designed to be a DMR and nothing you do to it can make it more accurate. The design uses the barrel as the spine of the rifle so there are too many contact points interfering with barrel harmonics to be able to do much with it.
If you buy one, enjoy it for it's positives and don't try to make it something it was never designed to do.
It is also a very awkward rifle to get set up on bags properly to do good accuracy testing with so that also takes away from a lot of people's results.
Learn to use the gas system and understand what your adjustments are doing and you can tune it to any ammo in a very short time. I've shot everything from 110gr handloads to 175gr loads and it will reliably cycle them all if it's adjusted correctly. You could over-gas it and have it cycle everything but that would just beat up the gun and your shoulder.
How often do you actually swap to different loads anyway. Any reasonable person would find a load the rifle likes and then stick with it. Being able to put 5 different loads in a single magazine and have it cycle them all nicely is a stupid test that proves nothing about the rifles reliability.
Some days I regret selling that rifle. I just wasn't shooting it as often as I should have been and wanted something else so it was an easy way to get the money for my new toy.