Yea, I do think it's appropriate to factor in the possible cat noise factor, because the stakes are pretty high if he turns out to be loud. Getting booted out of your apartment wouldn't be fun. And if he turns out to be quiet, nothing is lost.
All three of mine are talkers. Serafina is by far the loudest, and she'll caterwall away when she is bored and I'm around doing something, not paying attention to her. Gaga makes a ton of noise when she is unhappy (like when I've boarded her in various places), and at home she'll often grab a toy ball and start caterwalling to tell me that she has a ball, is coming to me, and wants me to play fetch with her. She's giving me fair notice, which is very considerate of her
Other than in those situations though, I'd characterize her has a pretty quiet cat. Neytiri actually has a pretty loud voice too, and seems to most often uses it when she is playing with some sort of solo toy, like a small toy mouse and is batting it around. I guess she just likes "monologing" about her prowess and adventures.
When I last lived in an apartment, I had two moggies that were both very quiet. They would talk with soft voices sometimes, or have small meows when they were expecting dinner and such, but very quiet for the most part. The funny thing though was that the people below me once told me that sometimes at night it would sound like a herd of elephants up there to them. I guess 10lb cats jumping down from cat trees or perches or whatnot, and thudding onto the floor and such does make some noise when all else is quiet. Anyway, they were nice people and never made anything of it.
Better safe than sorry.