DescentBB

I've quietly enjoyed Descent over the years and decided to revisit it recently, but something's been bugging me ever since I got rid of the old Win98SE box I used to play it on...the turning speeds are much, much slower than I remember. Makes it more difficult to quickly engage surprise attacks from the rear, and we all know how those robots love their ambushes.

I could easily get back to the old level and then some by using mouselook mode in D2X-XL, but even that doesn't feel quite right, and no such provision is provided for joystick mode. D2X-Rebirth doesn't provide the option for faithfulness-to-the-original reasons.

Part of it could be that I played it with a Spacetec SpaceOrb 360 on the older machine, and it's said that the drivers actually eliminated the turning rate limit in Descent II. Confirm/deny?

They did. That was why some people considered use of the SpaceOrb cheating (controversial, I know; not everyone agreed, but I remember hearing about it). D2X-XL now sets a maximum turning rate regardless of controller, though; I'm not sure precisely what Rebirth does but it's possible that the SpaceOrb used some kind of hooks into the original game that don't work with source ports anyway.

So the faster turning rates even applied in multiplayer? Nasty, and unquestionably a cheat in competitive multiplayer. I didn't get the chance to play D1/D2 multiplayer until very recently, when I got together with some friends for D1X-Rebirth co-op, so I wouldn't have noticed that at all.

If nothing else, I believe the way D3 and how D2X-XL is supposed to do it for mouselook would be ideal: make it a server-side option so that nobody has a competitive advantage. I don't see the harm in allowing higher turning rates for co-op, at least; if anything, the other players would surely appreciate being more easily able to blast bots coming from all directions, especially Thief Bots and Lifters trying to be sneaky...

Well said Sirius.
It could be the old DOS drivers too. Now that everything is 32bit (or emulated for us 64bit folks) that is doesn't work the same isn't too surprising.
It could be that it interacted with the fps as many things in D1 and D2 were dependent on fps; homing missiles for example.