When I get through S2 and3 I’ll tun the films on LD before plowing into the animated series and TNG. I have the BD set for the latter and the purist in me is already saying “couldn’t they have branched the effects there as well despite being native NTSC? I wouldn’t mind the old ones!”
In TOS, the original effects were all done on film, so it was easy to stay true to them during the remaster. I’m glad they included them because that’s how I choose to watch the BDs.
The HD effects in TNG are for the most part very tasteful representations of the original effects and integrate nicely with the remastered live action; they didn’t set out to “improve” them, just make them look like they got a detail upgrade so they blended well. Many of the effects were done on film, so they technically are the originals. I never felt while watching that I was missing out by not seeing the NTSC effects.
The NTSC transfers were horrendous and the tests they did with upscaled effects looked truly awful. Had every 480i effects shot been deinterlaced to 480p, upscaled to 1080p, and spliced in with the new film transfers, they would’ve stuck out like a sore thumb and taken the viewer out of the experience many times per episode. Even though it only happens in a few episodes, I know instantly when they switch to an upscaled shot because they couldn’t find the original film. Takes me out of it every time.