What is in OS3.5 or 3.9 that isn't in 3.1?

[Jupp3]

* Genesis Internet connectivity

With unlicenced, but fully working AmiTCP

* Full colour icons

I would hardly call 8bit icons "full colour"

It's also worth mentioning that you can get many of the advantages (same or similar) for free from Aminet. The mentioned comparison was (obviously) againist plain 3.1 with no (free or commercial) extra tools / patches / programs installed.

Of course this was 6 years ago so some of it is a bit out of date. These days people are concentrating on AmigaOS 4.

Mostly different people (H&P did 3.5 & 3.9, Hyperion is doing 4.x). Of course some "external contributors" might be the same for all three projects.

But indeed, most "amiga people" nowadays focus on AmigaOS4, MorphOS or AROS.

[Jupp3]

most if not all advantages with OS.3.5 or 3.9 can be downloaded from Aminet but these take alot more work to install and dont always work as well.

And some others might also work better :-)

With OS3.5 and 3.9 you get pre-set feature set, whether or not you like certain features or not (which CAN be edited, but that's not far from the said "aminet installation" way)
Personally I chose to at least use a better way to handle big hard disks, probably disabled some others aswell. Can't remember, it's so long ago :-)

Oh, both of them also add one additional reset when you power up your amiga (which can result in 2 boots if you have blitzkick installed (as you should) but you CAN make all the rom updates with blitzkick, took a while to figure out how, but I can't remember it anymore)

Personally the biggest letdown with both was the fact, that neither one comes with registered MUI.

[Jupp3]

OS3.9 you get everything installed automatically while with WB3.1 you have to install it manually.

And that's where the biggest problem is. Assuming you already had 3.1 installed before, you likely already have patched many things (big HD support, various WB patches, for example) and with the installation you might end up "patching something twice" and finding the problem... That might not be too easy. For example handling big HD's can be implemented in seweral different ways, some of which are specific to some hardware (Power Flyer, which I have, for example)

You might get bored hearing about big HD support, but that's where I had most of my problems :-)

3.5 was supposed to come with full TCP/IP (it was supplied with MiamiDX demo, and the full version was to be made available later, which never happened)
I was rather disappointed (just becouse it was one of the most hyped features) to find out that 3.9 still didn't have a unrestricted&legal TCP/IP, but I already had one from Netconnect 3, so it didn't bother me too much :-)