I believe that there are plenty of great sounding 34" B strings out there, but I think the 35" does sound and feel better over a 34", all other things equal. I understand what Ken is saying, that might not mean much comparing one bass to another, but there are lots of luthiers out there who've done the comparisons and refuse to build 34" 5+ string instruments because of the noticeable difference. Those guys stake their living on their opinion that 35" is better for the Low B.
Silly as it might seem, if 35 to 34 didn't matter, then 34 to 33 wouldn't matter, nor would 33 to 32, and ultimately we'd all be playing short scale instruments.
I am one who seems to notice fairly consistant advantages on 35" scale instruments, even on those that I don't necessarily care for, such as an Ibanez BTB or MTD. Those have good B strings, but I just don't care for them. I also seem to consistantly notice fairly poor characteristics on most all 34" scale 5 strings , even on instruments that I otherwise really dig, like the G&L L2500 and Stingray5. Those last two instruments I really like, but gosh that B string just feels floppy compared to most any 35" instrument I've owned. But they both sounded great in the mix and weren't necessarily a problem. But they did feel much different such that I had to alter my playing style a bit to compensate, specifically by not fingering that string to hard in the low register compared to how I finger the others. Otherwise it would really rattle against the board too much. I don't seem to have that problem on 35" basses. Yes, the other strings are tighter too, but that seems to be less of an issue for me than a flimsy B string. I can see how others would be on the polar opposite.
I will give Ken props on the Modulus thing. My Q6 had a heavenly B string. Even the 5 string Flea bass has a very solid low B, but I have to say it's still not as tight feeling as most of my 35" basses.