no, wouldnt go with fonesafe. just google fonesafe tmobile. you get dozens of people complaining about the company. if its just one or two people complaining, fair enough, but when more than 5 people angrily complain on the internet and their complaints are reasonable, thats not at all a good sign.
i have been trying to cancel tmobile phone for ages, it takes quite long time just to speak with the customer services and then the cancellation department. all try to convince you that sticking to tmobile is a good idea. even if you manage to cancel the contract with tmobile, you still need to make another phonecall to cancel the fonesafe contract. if you just cancel the tmobile contract, you will still be billed for the monthly insurance.
i would avoid tmobile. o2 seems better. they let you leave fast if thats what you want. and joining is also super-easy. no pushy sales about the insurance either.