Honestly if your current setup is working well for you then you really will not get an upgrade.. If your really wanting to go with the flex then all you need to do is get a measurement of your cage and then divide it by half and this will give you a rough estimate of how much you will need for each cage. Since your boyfriend is good at wiring then I would solder the wires to the element, just as stong as a crimped connection but cheaper. I wouldent go with a dimmer as you will want more control then a dimmer can offer. Ther themrostats on the market can offer you 1/10th of a degree accuracy for about 100 bucks and will control all of your cages that have the same size element and same volume. Let me know if you have any other questions on it