Version 'C" stupid question

[JDPratt]

This is probably a stupid question, but...Does the new Version "C" come with the Carvetight system or is that an additional add-on? I need a third machine and I am a little confused in the shopping area of the site. Just trying to figure this out so I know if I need to upgrade to the CT at the same time as purchase, it comes standard, or if I need to order another RC (kind of makes a difference if I am ordering extra bits as well). Second question. I am still running sandpaper belts on my two machines with no issues so far. do the kevlar belts really make that big a difference. Should I just go ahead and upgrade at the time of purchase?

John