I was making the same decision this time last year. I picked up the ASW-10 sub, TC2, and was waffling between the TST1 towers (which were on sale for around 200ish at the time) and the TSBLs. I ended up opting for the bookshelves and haven't regretted it.
However, since they have the 20% off sale now, I just got the towers as well. If they are a big upgrade I plan on using the TSBL's for surrounds. If they aren't I can always ship them back and get the dipoles for surrounds. The speakers came in yesterday and I've only had time to get a quick first impression. The towers seem louder but I think the bookshelves sound a bit cleaner. With the grilles off the midrange woofer on the bookshelves is noticeably larger and I'm wondering if that's why they sounded clearer listening to music. I do prefer the tower aesthetic, but unless a few days of listening changes my first impression I don' t think they are worth the upgrade cost.