Looks like that will be a nice set-up.
Upgrading speakers typically improve you system more than upgrading your receiver, especially considering you are coming from HTiB speakers. Unless you are looking to upgrade your receiver for a specific reason, I would look to replacing your speakers first.
The only thing I would look at would be replacing the sub with one from a different company. Not that Axiom subs aren’t great but for the same price you could get something from eD, Epik, or the new MFW-15 (if you’re willing to wait). Aesthetically it wouldn’t match as well as the EP-350 but from what I have read you would be getting more performance for you money.
Best of luck in your upgrade.