I have 3 modded MJ's, 2 900's(Sureflow kit) and a 1200(original DIY style), one was a little noisey, replaced the impeller shaft with a carbon fiber one, noise was gone, the other two work great and are basically silent, my vote is for Maxi-Jets(ultra reliable and a little more durable than the Koralia's, IMO).
I have a Vortech too, that thing is the best, I plan on replacing the MJ's with two more when I can afford them. Good luck in choosing which ones to go with if that was the reason for the post.
Matt