Some like the 3.5 version better. But never ever owning one, I have always loved my 2.8 version. I think the bokeh really looks nice from it. Maybe Reagan can give you some pointers on letting things go.
In my case, I have found my 3.5 AI version has lower resolution than my 2.8 AI-S copy
By the way, Here's a listing for a really nice Nikkor-Fisheye 16/3.5 AI from Germany seller if someone in EU interested.
