I have been installing upflush toilet systems from time to time for over 5 years now. I have used the Saniplus system with the tank that sits under the toilet tank. The toilet and pump system come as a unit. My customers like them, have no issues with blockages, and I have not had a call back yet. Some of my installations included connecting a shower to the unit as well as a lavatory. With that system if you are connecting a shower to it the base of the shower must sit on top of a 2x8 platform or you'll need to cut into the floor for the shower trap. I installed another unit that had the tank under the floor, a customer purchased it a the big blue box store. When the jacuzzi tub drained the tank would not keep up with it. A call to the manufacturer resulted in a replacement larger pump being sent to the customer at no charge (other than my bill for swapping it out). Based on my experience I would recommend the Saniplus system. If your application will allow it you can get and extension to put the tank on the other side of the wall from the bathroom. Do be aware these systems do not recommend flushing feminine products or sanitary wipes, they are strictly for waste and toilet tissue.