When I first got my Axioms, I chatted with Alan and was going to go M22 bookshelves. I told him more about my space and cubic volume, and quickly realized that for decent sized rooms, even with a big powerful sub, there were good enough benefits in output performance of tower speakers (M60s in my case) to justify them.
I've never looked back, but I know that some people really love their bookshelf speakers too. Heck, I'm using M3s for surround and overhead Atmos/DTS:X use, and I love that I can push them down to 70Hz if needed which is great. With a good bass management system, my M3s blend wonderfully with my M60 and VP180 front soundstage.
When I first got my Axiom M60s, I was in a room that was about 12 feet x 40 feet x 8.5 feet tall, so pretty good cubic volume. I then moved them a couple of years later into a space that was about 11 feet by 15 feet by 8.5 feet, and they were clearly "more than enough" for that room and bookshelves would have worked great for that smaller room.
So how does that help you? I don't know, maybe just that you can have a great setup either way, but if you get into a decently large space, you will benefit more from the output capabilities of a tower speaker.
