This is probably a bit outdated and I'll get likely nowhere with it, but.....Items purchased a-la-carte inside of the Custom Shop are not transferable to another user or other account. We are working on this to allow Custom Shop purchases to be transferable. More information to come.
Collections that are purchased in the Custom Shop can be transferred, as they are provided a serial number in your account.
Individual T-RackS processors purchased from the IK webstore can be transferred as of T-RackS v.4.5.
In the bold, it almost sounds like you can transfer something that you bought that was T-racks. Like for example, the 432 for example. If not, this is silly. I've always been able to transfer stuff with a SN (with the transfer fee of course) so not sure what is meant of "as of 4.5"
Clarification needed. Thanks
