I been using flawless-iptv.net for over a month 0 problem so far I watch the Brazilian Gp in full HD without any issue or buffer... Better than dexter and that crap gears tv
Never used lentech but just started using flawless and they seem reliable. A couple issues from their content providers but they are usually fixed in a decent time, and they let you know whats going on. Lots of activity from their facebook group and quick responses from their admins. So far I am happy. It's all Canadian, US and UK channels. They do have a 24 hour trial.
I'll probably do another month or two before I hopefully save money and go for a longer subscription. I have been burned before by others, so I am still wary of any service.
Flawless is good. Better than Dexter. Much less downtime. Watched UFC 205 in HD. didn't buffer once.