Good morning. Just some thoughts on your situation.
1. Aperion is a good way to go. Not only do they get good reviews for their products, but also their customer service. The no-risk return policy is awesome, in my book.
2. Good receiver choice.
3. Good sub choice.
4. The big difference between towers and bookshelves is normally the bass output. If you auditioned comparable speakers, listening to towers and then to bookshelves without a sub, then I would suspect that the towers would win every time. When I went to audition my NHTs, NHT made a set of bookshelves and a set of towers - they were identical except that the towers were like the bookshelves with a taller cabinet. Honestly, the towers without a sub sounded identical to me compared to the bookshelves with a sub. I mention that for the next point.
5. If you put towers on top of that TV cabinent, the cones (and I think this is especially important for the tweeters) will be raised higher than they would be if the towers were placed on the ground (like they were designed to be). I think that tweeters are typically supposed to be at/near ear level, so if you put them up higher, they won't have the same effect. I'm not saying it'll sound bad...I don't know. Just something to consider.
6. The towers that you are considering are rated at -3dB at 55Hz. Not incredibly low, so a sub would still do you good.
7. If that TV cabinet isn't real sturdy, the bass from the speakers is going to shake it...and the TV.
8. Whatever your choice, it's virtually guaranteed to blow away the sound from that TV!
Adam