NHT tweeters

I think that he would do fine with the SB1's or SB2's.
The 1's dont respond low anyway and the 2's would be crossed over around 70 or 80Hz anyway in a surround setup.
Not that what you say doesn't have merrit; it does.
But in a mid-fi surround setup I don't know that it would really matter.

On another note; why not keep your Super Zeros? They are on par with the SB1's and I dont know that the SB2's would be any improvement in this situation. If you wanted to really improve this small aspect of your surround setup why not take Flrnlamb's advice and get a sub just to reinforce your side speakers? Get something like Martin Logan Dynamo and send it everything below 60Hz while sending the high-pass out at 70Hz to the amplifier driving the Zero's.

2cents.

"I'd like to get side speakers with a decent lower end to them, but that are still wall mountable." (tsrart)
Here's your problem with that thinking. You're going to have an unbalanced/non-accurate sound by placing lower bass up against your wall with those speakers! They'd have to be seroiusly EQ'd, and it's not really the way to do it. The bass modes all pile up on the walls/corners, and reinforce the bass waves. Also, the wavelenghths of bass that are that close to the wall will also be amplified beyond the rest of the frequency spectrum, causing you to be forced to bring the bass balance to those speakers down anyway, to bring it into spec with the rest of the mid/high's! It's better to put smaller monitors on the wall, and let powered subs elsewhere handle the bass in that situation. I say this from 20 years experience. Unless treated properly, those wall mounted speakers will "boom away", and not be flat within their frequency range, which is what's intended by the speaker maker and mixers themselves! Balance is the key, and proper setup is critical. I wouldn't!!!....

Not enough dif. for surround sound.
The SB models would work fine.
A better side speaker may actually be the Von Schweikert TS-150 though. IT uses a soft dome tweeter with a polymer coating. It also has a dipole/monopole button on the side.

Good luck!