Is the only difference in ktecs flasher and the rs tuner the price?

Well with the K-Tec renflash you pay for the device which allows you to remotely upload your factory file and get K-Tec to remap it and then allow you to download it and load it to your car yourself. But if you want to remap it again say you upgrade cams or remove the de-cat you can pay £149.99 for them to do you a cams/de-cat remap.

RSTuners you take your car to them and they will remap it and a good job they will do.
 
What's to stop one person on here buying the K-tec unit and then lending it to everyone else on the site? Can the unit recognise that it's a different car?
 
looks like its the same basis as a Dreamscience DSF3000 that people with Fords use. If thats the case then yes it will recognise its a different car and wont be useable. The DSF3000 holds your stock map on the unit whilst it transfers the upgraded map on to your ECU. This stops you from passing the unit on. Unless this unit comes with 'lives'
 
it will most likely lock to the car, and will have to pay for a new license to use on another like the rs tuner.
 
Yeah as above these devices tend to lock themselves to the car, meaning that you have to buy a new licence from the manufacturer if you buy one second hand. Generally the licences are slightly cheaper than the device itself but not by much.