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When this arrived I was surprise how small it was compared to my failed unit. I was a little worried until I compared the pump ratings and saw that this one is made to eject the water fast. Which makes sense. My old one had much more interior room which allowed more of the water to sit and stagnate. This one wants to pump it out asap with little water remaining in the tub. The snap top is a vast improvement over the screw top I had before. The only tricky part is that the mesh barrier uses notches in the top's reinforcement ribs to hold it in place. This is a bit of a pain if your sump access doesn't have a lot of top clearance. This goes double for the wires. They run through notches in the side wall and are sealed off by the top closing down on them. So, for me, reaching under the floor at an angle trying to close the top while lining up the mesh and the wires at the same time is quite the feat. But, I had to do the same with the old one just with screws added into the mix. I think a side wall bushing for the wires would help the design.
The inlet ports are pretty close together. This make them tricky to cut with a saw. Which, you have to cut open the ones you want to use. I recommend drilling them out if you have a bit large enough. I had to do some trickery to get the ac drain hose to work. I opened up the 3/4" hose fitting on the outer right (in the picture). Mounted everything in place, than to find out that my ac drain line is 5/8". Had to run out to West Marine for hose and one of those hose butt adapters. Moral is: double check your hoses sizes before you cut the inlet pipes off. Because, if you guess wrong you might have ruined your new sump.
There is also a small over flow drain at the top near the pump. I ran a hose off of this down into the bilge next to the bilge pump. That way if an overflow does happen, hopefully, this will keep water on the marine plywood shelf to a minimum. However given it's small size, I don't think it would keep up with incoming shower water too well.

All and all, Installation wasn't terrible, the pump clears the sump quick and quietly. I'd recommend this sump but only with the precautions listed above.

Update: Everything is still working just fine after one season of daily use. Only with one issue; with the lid completely seated/snapped in place the pump will run continuously. Not sure if this is some kind of vacuum lock formed by soap scum and the check valve. I've stopped futzing with it. If I leave one snap loose on the lid the problem doesn't happen. With the pump clearing the water so fast it doesn't seem to be an issue and there's not enough to slosh out why underway.

2nd Update: Well, it's in the garbage. I found it too much work to clear the pump head of hair and scum. It started out as a monthly chore and then became a weekly one. I bit the bullet and got a Johnson Pumps Grey Water system. It uses a diaphragm pump instead of a centrifugal one mounted in the Attwood. It's similar to your waste pump and can handle soap blobs and hair relatively well. The biggest down fall of the Attwood is the pump. The impeller is good at moving clean water but fouls too easily with soap in the mix. I recommend staying away from centrifugal pump sumps all together. Mike from the Lifesaport live-aboard blog