I have had both models, pre 2021 model and 2021+ model.
My honest review? get an older model. This is not a run and gun weapon, its designed for long range work. That light profile BS is 100% not for me.
Great platform and heavy AF but its worth it. I hate that HK USA cheaped out and went with ****ty MLOK rails and Magpie grips. I prefer the V3/4 grip and Quad rail or Geissele.
Aftermarket parts are nil and all teh good stuff is serious $$$ so there's that...
If I couldn't source a pre 2021 model at a "decent" price I would 100% pass. unless you can score one at a deal like some there members have gotten via taking teh Hk class (40% off).
If you don't have an MR556, id strongly suggest that you pick that up instead as teh 2021 profile actually works in its favor as its SIGNIFICANTLY lighter and looks great. Aftermarket parts are hard to find in HK flavor but because its "standardized" in most AR aspects its easy to tailer to your preference...
Those are my $.02
Now if you wanna chop the barrel and go 13" assaulter MR762... then just go for it because that style is 100% 🔥 and worth the $$ 🤪
For what its worth, on my 762 I have a Geissele rail, trigger and charging handle, these 3 parts alone are north of $1500 on teh current market. g28 stock & Hk grip (which aren't 100% essential) are another $600. A5 selectors & trigger guard (again not 100% essential) are $200. Factor in teh cost of teh base gun @ $4k and im into this for $6k before glass... and you know how much good glass is... PMII 5-25 on era tac @ ~$3.7k and im @ $10K+ for my spec.
Older pic for reference, I've since added a few other bits and bobs but you get the gist.