I play with SPQR now, and like it very much. Far more bigger battles, and also longer. Unit defences are adjusted around 40 or so, and this enables the combat lasts very long. At least enemy units don't rout in a few seconds. Once I was attacking enemy city, my hoplite and enemy's hoplite locked each and fought so long that I have to find other route in order to get to city center and surround the enemy hoplite.
0-recruit time, combined with AI's economical advantage in H/VH campaign, makes AI army much bigger and far more frequent. This makes earlier campaign very challenging.
Additional cool units and new skins.

Cons...mid/late campaigns somewhat boring, unchallenging. You have huge money/population, with this you can build huge army in just one turn. Loss of entire army doesn't seem too much disaster. Self restraint required(like not recruiting army from conquered city in several years).

As for RTR, I don't have much to say. Just I don't like longer build time, and too much *realism* things(like quarry to build stone walls). But ZoR(Zone of recruit?) is good idea.

Personally, it will be good if SPQR with ZoR.