I'd probably skip the Paradigm sub. Look into HSU Research, they have a Canadian distributor (assuming you are in Canada). Dollar for dollar, you'll get a lot more for your money.
I've owned quite a few 'digms and found the Monitor series to be fine for movies, but as you seem to be finding as well, I found them wanting a bit for music. The 3s aren't going to make anything better, they are boomy, IMO. The 5s are clearly the best of the bookshelf speakers in the Monitor line, but they are also quite a bit more. What you might want to do is give the
Axiom line a look; they're also Canadian natives, as well as PSB. For the price, the Axioms are a bit more musical to my ears, and you should be able to get a pair of M22s for somewhere between Minis and 3s, and a pair of M3Tis for surrounds for less than Minis.
The Monitor 7 is a Monitor 5 in a big enclosure. The driver array is NOT the same as the CC370, which is a 2-way vs the 2.5-way of the 5s and 7s.