I just picked up a CW9. First impressions are pretty favorable.
Overall I like the gun, size is perfect, trigger is long but very smooth, sights are adequate.
The only issue I have so far is the mag well.

Has anyone done any modification to open it up any?
Looks like it would be just a few minutes with a file or sanding barrel in a dremell  at low speed.

Just curios if anyone has tried it yet or if anyone has any valid reasons why it's not a good idea.

Thanks in advance

Nothing?
I guess I'll have to be the first.

A slight bevel shouldn't cause any negative issues.

But, I can't say that I've practiced reloading my Kahrs to the point that I feel the magwell is holding me back.

I've been shooting the piss out of mine for years and never miffed a reload. The magwell is very forgiving IMHO.