I have done this process many times and it always looks far better re-encoded than letting the TV do it. You don't get a lot of problems on the re-encode partially I think because you have resized and then processed the image, so the original blocks have now changed shape, had their edges less defined and moved position. So you don't get the typical problem of the exact same blocks being re-blocked if you know what I mean.
Anyway, don't take mt word for it, I haven't tried every TV out there, so try it yourself on any letterbox title and see how you go.
But doing it properly, it causes no offensive artifacting and gives a far superior viewing experience when I have done it in the past.
(Of course you could do a horrible job of the re-encode if not done properly!)
(Edited to fix at least some of my Dyslexic typing)