A buddy has a 3ES, which has basically the same amp section as the 4ES and it's pretty stout. He has a VERY large room and after I calibrated it, it had no problem handling it (with a mish-mosh of speakers, none particularly sensitive, dual subs). S&V also tested that receiver as capable of an actual 100w with all channels driven I believe, and regardless of their testing method, that's respectable (my receiver tested as 92w all channels driven).
What exactly is the issue with your sound? Me personally, when I had the Monitors I had upgraditis too. An amp is going to bring out both the best and the worst in your speakers. When I did some aduitioning and once I got my SACD player, I quickly realized it was the speakers that were holding my system back. I'd say go listen to some speakers and at least get some ideas as to whether other speakers will suit your needs. I would also maybe recommend looking for a used amp and at least save yourself a little cash if you decide to go with an amp. Maybe you can find a used Marantz MM9000 or a used Rotel, Adcom, Parasound, etc... Outlaw amps are great too.
Have you thought about maybe just a 2ch amp for the 7s? The 4ES also has probably the most flexible bass management I've seen - how do you have your x-overs set?
