Real world problems, lol. I have used sum 3d way back in 2012 and it is a powerful cam but it really is too much for a new user. Millbox is a simplified sum3d click n go style but powered by sum3d's engine in the background. I hear the newest version and strategies in millbox utilize the 64bit windows and runs much faster now. Hyperdent will calculate faster than sum3d and on the 51D full arch cases it will mill inward from the side of the disk in order to get amazing anterior results on full arch cases. But again it is a very powerful cam and may require good training. I forgot what the preciso cam is maybe a dumned down version of hyperdent.
I personally run DS-Cam Dental Softworks or wieland cam on all my wieland and vhf mills. Fast simple and easy to use. Other options are Work NC and a few others. Just make sure what ever cam you get can run multiple types of mills just in case you get another brand down the road ad all the mills are cammed off the same cam resulting in one database of disks and you not having to run 2 to 3 different cams and have 2 to 3 different sets of disks. Others will soon chime in with more info, just do your research before you commit, also sum3d and hyperdent will run demos on your mill if you already have one so you can see the results for your self.
If i were you i would go with the Roland DWX 51D, what Preciso were you looking into 4 or 5axis?