There shouldn't be any risk associated with leaving it late to renew a domain, because you expect that if your money is taken, and you get confirmation of renewal from the company responsible for renewing it, then you should be confident that your domain has been renewed.
The only risk associated with leaving it late is that you yourself forget to renew, anything other than that and there should not be any risk attached.
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Rather than telling a customer their domain has been renewed, when it hasn't been, how difficult would it be for the renewing company to have a script in place, which checks the who-Is to make sure the renewal is confirmed, and if not, it notifies the company and the registrant that the renewal hasn't taken place, can't be that difficult to have something like that in place?
100% agree with all of this!!
I can see from comments in this thread that other people perceive my late renewal as wrecklessly sailing close to the wind however the way I have always looked at this is that if I am legally allowed to renew up to X date then there should be no risk whatsoever at leaving it to this particular date to renew - as you say the only risk is that you yourself forget but I have always been pretty organised in this respect and only ever dropped domains I have wanted to