shockwatches are garbage. period! i've delt with the crown info links, which i feel are good units. don't know much about the others, if you ask me it's all a waste of money. their great at first but wait until operators start damaging them or equipment starts to fail. repair costs are always expensive! again i feel these units are just some sales gimicks, they claim that they help you do all this stuff, but it's just a bunch of crap that you really do not need. just get a good filing system on each unit and keep track of everything yourself. when you recieve any paperwork from service work performed just throw it into the corresponding folder. this is only my opinion. good luck on whatever you choose.