^^ what she said .. although I don't think I can quite claim mine has been in use for 8 years yet.
(Wow that's awesome BTW.)
Anyhow I've used two different LG4 models as sump returns. One is a fan-cooled model and one is not. The one that is not fan-cooled is what I'm currently running on my 75g. I would recommend getting one with a fan because this pump runs SO HOT that I'm not comfortable running it without a fan blowing air on it. I use a little 4" computer style AC fan, it just sits on the floor and seems to keep the temperature under control. I tried running it without the fan on and after a few hours the whole basement had the smell of "hot electrical equipment" and I've never tried that experiment again. It's so hot you can't touch it. I'm not sure that's correct, but then again the pump has been running for almost 4 years now so at least with the fan it's a good arrangement. In fact I'm wondering more about the fan I'm using, it's been on for like 4 year continuously, and I'm wondering how much longer I can expect it to keep turning.