I have one and know others personally that have them, and know many on the internet that use them. I like it, but I wouldn't call it the best thing since sliced bread. The ultra's are heavy, but they handle recoil well. Tuco's is the first problem I have every heard with them. I hear they have good customer service so they should hook you up. While it's in there you should have them do a trigger job on it as well.
From playing with mine, others and talking to people on the net I don't think the accuracy from them is anything outstanding, but they are great for the money. If having a single shot really bothers you go ahead and get a mossberg 500 or remington 870 combo with a cantilever mount. I have seen pretty much the same accuracy from these set ups when you find the right load. I think this is the key with slug guns, you just have to invest the time and money until you find a slug it really likes.
The trackers are lighter, but they kick harder as a result and they only have open sights unless you can find a gun smith to mount a scope on it. Some will, some won't. H&R doesn't recommend it. They are cheaper too.
I wouldn't be expecting half inch groups out of them at 100 yards either, let alone off hand

. Considering they shoot a 50 caliber bullet (half inch in diameter) that means all your shots would pretty much have to go in the same hole. I haven't seen one yet that can do that, nor have I met anyone that can shoot one that well. Average is between 2 and 3 inch groups from a bench at 100 yards when you find something it likes. Providing you can shoot it that well.
Good luck,
Paul