I would not worry about the number of rated watts the speaker can handle. I was told from a representative at AV123 that they don't publish that spec. I can tell you that this is a no issue for Rocket speakers. They can handle just about anything you can throw at them. More amplification will really make them sing. I can assure you that they can handle alot more power then the Axioms. I've had both setups and...uh yeah, the Rocket's handled more.

Really, it's not a deciding factor, but the Rocket's sure can handle alot. As for your question about built quality and wanting one that will last, I believe both companies are using good quality components, so both should last a long time. I would give the edge to the Rocket's though if I had to pick one simply because the materials are more durable. These are heavy speakers!

You will also get a much better finish with the Rocket's as well, if that matters to you. All real wood veneers with high-glass piano plack endcaps. They look really nice, especially compared to the vinyl you'll get with the basic Axioms. Now axiom does have some nice finish options, but you will pay alot more for them, if you decide to upgrade.
Also, take a look at the center channels in each of these setups. If you are going to be doing alot of movie watching, I, again highly recommend the Rockets. The 'Bigfoot" center channel is just plain better than the vp150 is.
However, the most important factor here, is the type of sound you prefer. These 2 brands are night and day as far as how they sound. You'll need to audition and see which one you like better. I've had both, so thought I'd share my thoughts. Good luck.