Thanks for the replies, guys. I knows everybody's ears are different, so one person's good fit could be another's lousy one. I was just thinking if the IE80 could serve as a benchmark for comparison, I might be able to gauge how the IE800/S might fit me, since I don't know of any dealers in my area that would have a pair to try. (Nothing came up in the Sennheiser dealer search.) But it sounds like they are different enough that making a direct comparison would be tricky.
Very different from IE80,
Ie80 had a large bore, hard to insert deeply, very shallow typical fit, always pushed them back in, got best comfort with double flanged
IE800 has a deeper fit, inserts normal depth, only requires adjustments if your ears sweat and if they get slippery, wipe on shirt or paper, also wipe the tips, ready to use again without issues.
Sound is also extremely different, no actual similarities,
IE80 is bassy, somewhat smooth on the top end, no focus on instrument separation but very large soundstage size, amazing for a IEM.
Ie800 is V-shaped with energetic top end, a lot of sub-bass, not a lot of mid-bass (like IE80), recessed mids, strong treble with excellent glimmer, instrument separation is in top 5 of IEMs ever created regardless of price range, soundstage size is not large or spread, rather within normal boundaries, it is the instrument separation that makes it so impressive, very revealing