Greetings folks. I have two of these boys, and although I too think that they're a great bang for the buck, putting them in the same league as a RNC is a bit off i'm afraid.
I also have a RNC, and for as good as it is, you can't go around its faults (and it has a few). The electro harmonix pres have no faults that i can think of, except the absence of a huge amount of gain, wich can be circled in a number of ways (different power supply, etc).
Even that, I can't really consider a fault, since nowhere on the Electro Harmonix website is it stated that this is a "stellar do it all pre for nearly nothing" (funny thing is: it is). Ribbons are risky with it, but it's fine with anything else you might think of, expect gain hungry mics, like old EVs or Shures.
Plus if you're putting your 80 dollar mic through it, you can't really expect it to turn your mic into a 800 dollar one - it's just not happening, if anything, it will further enhance the mic's faults. This pre likes good mics. The cheaper i can get with it and still be satisfied are my Oktavas (a pretty perfect match). For what it is, it's pretty revolutionary. A 200 buck pre that lets the mics shine (or not) and doesn't induce any artifacts, all discrete. 2 years ago I didn't even expected something like this to come out, ever. So enjoy it for what it is, that's my view on it.
I haven't modded or replaced anything on mine yet. It still works the same. My only gripe is that you really have to use balanced inputs (read xlr) or the self noise goes up dramatically. Hope that helps.