[BeardyMentor]

You are probably not going to see much of a performance difference between pulley manufacturers provided they are making the tooth profile to spec. (I would guess that any reputable supplier will be) As others have mentioned, larger pulleys are better for higher working loads than smaller pulleys. The biggest factor in belt life is tension, unfortunately this is also the hardest thing to measure.

If you want a particular brand of belt or an odd width, instead of Mc-Master Carr, try looking up a local Gates dealer. I have found that they will generally get you the same or better product in a similar time frame for less. I have a few that I go to, if you are interested, send me a PM and I can send you their info.