Endless debate: monitor + sub vs floorstanding

Have made a simple system with Peachtree Inova and Proac Sig 8 Tablettes on sand filled stands. Lovely sound I am quite pleased with though I'm considering either supplementing my beloved Tablettes with a sub bass (most likely the new Rel T5) OR grabbing a pair of full range floorstanders (likely used Proac as well).

Any thoughts on the relative merits of the two setups in terms of expression, detail, dynamic spectrum, musicality and also flexibility? Intuitively, it seems I may have more opportunities to play with and fine-tune the experience using Tabletttes plus sub.

I realize there is probably no perfect answer here. Unfortunately, my opportunities for a good side by side listening comparison of the two systems is pretty much nil.