I'd say get the XP3. I'm in the same process you are and I've been debating between the XP3 and a Fluval 404. The Rena's have been getting good reviews but I like the fact that in the Fluval, the foam pads are easily accessible on the side of the inside of the canister....therefor you don't have to remove the baskets to get to them for removal/cleaning..... and vica versa for the madia baskets.
the xp3 works great for me. i run it on a 55 gallon and i just clean the nedia once a week when i do a water change.dump the water, clean the media and plug it back up. it will fill itself when you conect it back up.
True the XP filters are very good but if you are deciding between that and a skimmer, I would choose the skimmer hands down. The filter while good at what it was made for, does not remove anything from the water but rather stores it. The skimmer will actually remove organics from the water before they break down and degrade water quality. As far as clarity is concerned, carbon will easily take care of that and I would encourage it's use.
75 galsalt...................what type of tank are you thinking of setting up....FO, FOWLR or mixed reef. Though it may strike you as a mundane question, it is important and I should have asked you this before.
dorian...........after you put the filter back together, it fills itself back up? That's great.............does it fill before you turn it on, or after? I thought you had to prime it by pouring water down a tube into it to fill it and than you can turn it on. Am I wrong?
you have to prime the pump the first time. then when you disconnect the hoses to clean it , it holds the water in the tube, so when you reattach the hoses it will fill itself. then you wait a few minutes to let all the air out. when i clean mine, i try to put some of my fresh water into the canister to avoid alot of air bubbles getting pushed into the tank.
i have to agree with the others though. a skimmer would be a good investment.pretty much a necessity if you are looking into a reef tank.
it will also pay for itself as far as water changes and overall good health of your tank.
im running a 55 gallon semi reef with the rena xp3, remora skimmer, maxi-jet 1200, and a mag 7 with a scyd in a loop setup.