Sorry David, hands down best pumps for reliability and quitness are the eheim units. I just think the eheims are over-priced in Canada (135.00 for a #1250) but you can get one from Danger Den for $65.00 (flows 320gph). They rarely leak (unlike the Mag-Drive I run, which I siliconed). Sorry I raped your thread.
P.S. I don't know anything about the hydrothruster 500, but the current debate I have is if there's any advantage to good pumps over 250gph. I still haven't heard anyone saying they cool better with the bigger unit in a standard setup, but if you get it, tell me how it works for ya.