If I'm shooting at targets and I'm not using my HW100 then it's always the 77. With minimal work (comparatively with these tuners) they shoot very well. Full length is a bit different from all the carbines we see everywhere so I'd say opt for that if it's on the cards.

Had a HW35E in .177 which turned out to be a pile of excrement so I don't think I'll ever have one again. I'll admit there are some decent ones out there though.