I've never heard the RC-30's, but I can tell you that I LOVE my RC-70's.
I have a pair of Mirage M760 floorstanders that I bought back in 1989. They are outstanding, and sound as good today as they did when I bought them all those years ago. They're finished in black ash vinyl, but look like real wood (Mirage does a good job with that).
We moved into a new house a year ago, and I bought new "stuff". While my old Mirages sound, and look, fine, I wanted something new with a nice finish to match the A/V cabinet.
The bar was set very high based on those M760's, and I couldn't audition the Energy's (no dealers nearby). So, I went with my instincts and other owner reviews and bought the RC-70's from an authorized on-line dealer who assured my that I could return them if I didn't like them.
Well, that was back around Oct.-Nov., and I still have the RC-70's. I have the rosenut finish, which is almost a dead-on match to the finish of the cabinet.
Based on what I've read from other RC-30 owners, I think you'll be very happy with them.