not trying to be an ass but most of the topics that are being questioned here have all been discussed previously, you just have to use the
and read through the threads. unfortunately a lot of them ended up with childish/nasty arguments but if you read past all that BS you'll be able to find the information you are looking for.
also contact the companies that offer these systems!! i'm sure they will be more than happy to answer your questions.
@edu09 - since you're in miami why don't you stop by Active? you could talk about your concerns with them in person and maybe they'll even give you a test ride! i hear thats all it take to get convinced lol.