As a practical matter the RTW tickets accrue cost for flown segments so quickly that once you have flown 2 or 3 segments there is zero remaining value on the ticket, thus cancellation of a RTW really only applies if you decide to not take the trip and cancel before taking any of the flights. Thus the TA's cancellation fee is relevant only if you think you won't be making this trip after all; personally I think it is a reasonable fee, a bit high (I would expect about half that, esp. on an LONE5), but switching TAs may cause you to lose any flights presently booked and it may not have inventory available for the same flight/date when your new TA goes to rebook.