I would just like to add that i have this identical problem, and had my clutch and throw out bearing replaced.

I experience the symptom of when i let the clutch out it takes 2-3 seconds for the grindy (almost hissy) noise to fade away, is that pretty much a sure fire indication that its a input shaft bearing?

I also have horrible loud, yet similar grindy noises when downshifting, or letting any load go on the transmission to slow the car down at all.

Also, if i'm going say 3000rpm in 2nd (or 3rd) and i just let my foot off the accelerator altogether, i dont get a nice smooth gradual slowdown, its immediately lurchy. its very hard to get it to NOT lurch when letting my foot off the accelerator EVER actually..

I know my transmission is hosed, i just dont want to face the facts (or bill!)