I've always had fantastic service out of my sequence pumps (owned 4? now), and would highly recommend them.
I did have a SEQ5800 once, but ended up selling it. Unless you've got a SERIOUS need - I'm talking 30' of head or a 1000+g tank, I'd consider something smaller. It was WAY too much pump for my 240g tank + 100g sump with 16' head - I had nothing but problems with microbubbles. I suppose a bigger sump (2-300g) would take care of that. In any case - be aware that the 5800 is a huge pump, and may be too much for you. No complaints of the pump - it was just too</em> much...