A few more reasons for the other charger:
(1) The ProSport, being a waterproof, just doesn't cool as well and electronics like cold. Air-cool when possible. Obviously, when you need waterproof, you need it, so I'm not picking on the ProSport for it's intended use.
(2) The ProSport doesn't have a desulphation mode, which is a good thing to do now and then.
(3) The Pronautic/Pro Charge has a display that will let you know what it's doing. If you don't have other monitoring, it can be quite useful. If you have one of the monitors in that first link, then this is not so important.
And yes, especially with Mainsail's instructions, you can install it quite easily!