I'm just starting to play with physics in 3dgs, obviously 3dgs multi-object physics needs professional, which costs quite a lot, I currently have comercial,

and I'm wondering from the point of view of perfromance, cpu usage, support and reliabilty, etc, etc, which is best physics system to use.

Any comments would be helpful.

Both are stable and perform really well, they have similar features and both can be expanded upon, but for that extra step of integration if that's what you're after, and willing to pay extra for it i'd go 3dgs pro.
But if you're cautious, play with newton for a while as it is an extremely worthy tool

Newton currently has some serious drawbacks, like lack of polygon collsion (so cant have models collsiing on models very well.. lack of primitive models besides cube and sphere )for insatnce cant do barrels), etc. Ventilator is working on a new plugin using the latest Newton library tho..

And... there are some more obstacles on integrating newton into an own project. You will have to pay attention on timing while initializing your physics objects. I had some serious troubles about that.

If you are using poly-collison go with 3DGS physics, otherwise, Newton will work just fine.

Thanks for the hints, I'm saving for 3dgs pro