I have a less favourable opinion on HT vehicles, i own one - the Tumbler and a few parts broke off and it was new. No mishandling or force used, pieces were just brittle. My evaluation is made up of these reasons 1) lack of high quality for the price - wouldn't pay more than $700 for almost all their vehicles, 2) glaring inaccuracies, 3) laziness and doing bare minimum with 2.0s and sequel cars. Just so I don't sound biased towards HT, I believe like Joost said, there's a market for both products but HT and Jazzinc are at extreme ends of the spectrum in terms of quality and price, and if you can pick up a good deal / bargain on a HT vehicle, then I'd say its good value but otherwise I don't think it's worth paying 800+ for their vehicle IMHO (depending on what the vehicle is, there may be that one that is worth it but I'm generally referring to their Deloreans, Batmobiles).
Now, for many Jazzinc prices out customers completely so HT is the only “affordable” option for 1/6 vehicles, however, we’ll have to accept some of those issues I just mentioned, quality being the main concern. I’d like to own a Delorean and I’d probably be ok with its issues if I got a good deal for it.