I don't really think so. HARP is fine for a toned down version of RM, but an improvement over DnD. I don't think there's anything wrong with it in that respect (I just like the extra detail provided in RM). Besides, I suspect a lot of the DnD crowds beef is that WotC (post Hasbro buyout) cranked out too many versions of DnD too fast. From a short-term bottom line standpoint that makes sense to do cause you get a huge buy-in... but it will make your customer base angry once they decide you're just milking them.
As for RM, they want to grow the customer base. I, personally, do not see RMU doing that as it stands right now. IMO, currently it's no less intimidating than previous RM's to the non-RM user. More so in some ways. Unless they pull back on the perceived complexity I fear RM's reputation with its critics isn't going to improve. Hopefully either the second round of revisions will improve things or, better yet, I'll just be proved wrong completely regardless.
Also, many of us here who know our, likely customized, respective RM2 or RMSS variants well may not see any point to switching if RMU doesn't present a large improvement in what we (and 'we' all have differing opinions of this) think are their deficiencies. There are things I don't like that I could simply change back (which leaves me wondering: Why change) but there are others that have long term impact which I'm not willing to fix myself. So, I'd stick with RMSS. But am I representative of the typical RM fan-base? I'm comfortable writing my own material, I don't need more rulebooks unless they have something new not released under the RM2 or RMSS umbrellas - and I'll only buy those if they're easily (for me) backward convertible. How normal is that among the overall RM customer base?
HARP is probably the better one to try gaining a new customer base with... essentially "RM Lite" (I know, there was a RM-Lite - but why try to do that again when you can just use HARP?).