If you're happy with the tone and want a bigger opening I think the T35 would be a logical choice. T20 is an .80 opening and T35 is .90ish, so you might want to drop a half or even a whole number on your reed strength if you go with the T35. I dig the V5 series- no baffle with a small chamber gives me a bright focused sound with quick response and very little edge. I used a T20 throughout college for classical stuff and still find it far preferable to other classically oriented tenor mouthpieces that I've tried.
I've never tried a T35 myself, but I play a Java (not jumbo) T45 as my main mouthpiece and feel like it gives me the edge and brightness I hear for jazz and R&B and is versatile enough to darken up when I want it to. It's chamber is a little bigger than the V5 and theres a medium rollover baffle. It's just about the same opening as the T35 and would be a good thing to check out if you're looking for a little more punch.