I have Invacare and dongle both. MY DME sometimes ask me to program chairs close to me as they don't like to spend the time with it. I spend about 4 or 5 hours helping crips like us program there chairs for free just to help them out cause they cant afford a tech to spend 4 or 5 hours with them. I like the dongle as once you hook it up you can leave it on the chair as they drive it and then go back and change setting without a lot of hassel. Some even get the hang of it and do it themselves once I so them how easy it is. They always want to pay me something most I'll take is gas money. Some vendor rent them out on ebay also. The real time is writing all the setting down on paper so incase the controller goes bad the DME has something to go by. Some you can save on memory stick or save on puter but I find writing it all down on paper is the best way.