Sy's poops have always been darker rather than golden. Hiro's too actually!
I really hope that you are right, it would be nice if I never had to smell those stinkies again. They were so strong and we have affectionately called him Syly-Stinkbum for most of his life. Poor guy. We did ask various vets about it but none of them had any answers. I can't remember if we mentioned it to Molly, maybe not though because we just got used to it and it didn't seem to cause him any issues.
When I was little my parents had a family party and they plonked me in front of the tv. There was a programme on about fish and they started doing a segment on Octopuses. Out of nowhere I shouted 'MUM! LOOK AT ALL OF HIS TESTICLES!' :lol: Obviously I meant tentacles and my lovely family still bring it up at gatherings now, 20 years later!!!!
Some years ago quite a lot of us with stasis/bloat prone rabbits for totally different reasons got together, & found that there quite a lot of factors which caused gut slow down without symptoms & then there was a last straw effect. Stinky poohs always mean that there are the wrong micro organims around somewhere 99.99% of the time they're in the caecum = uneaten caecals. However it is possible just to get them in the middle & end part of the colon so only the waste poohs are affected. Some of these microorganisms make toxins which slow down the gut, especially the really stinky ones. Add to that that he's a bit nervous - startles easily, then add a chest infection, (& Abx can cause a bit of overgrowth)
(You said he had a clean but stinky bum. IMO a bit of waste matter was getting in his anal glands & causing stinky there too, & this might have been why he was making your bed smelly. Rabbits usually clean out their anal glands themselves, as I think Sylar has done, but some need a bit of help.)
When we increase the fibre, the whole GI tract works more healthily & faster, so they can eat more as well as get more nourishment from hay & grass. The abnormal microorganisms can't thrive in this environment.I describe it as "starve them out & flush them out". I know it scares some people when we talk about low nutrient foods but this is actually how a rabbit's gut is designed to function, & stay healthy.
Whatever the management is the same - cut out the high nutrients & increase fibre, which is what you are doing, very successfully.
It's also possible that abnormal bacteria are causing another problem but the info is from 6 years ago & not proven. Some vets think that the toxins from the abnormal gut bacteria also increase the blood supply to the tooth roots causing dental problems.
I can't promise that his dental problems will stop completely without the colonic dysbioisis - some rabbits do, & some don't.
It's all making a lot of sense to me & I think this is a huge step forward.
Thank you so much for giving us another laugh.