I would just stick to using the FOSS (Free Open Source Software) X11/Mesa drivers for AMD/ATi. The driconf toolkit and add-on s3tc library complement the free driver very well and are more stable and compatible.

Nvidia makes great UNIX drivers. AMD does not. The free drivers are actually closer to the quality of Nvidia's closed source drivers anyway.

You are certainly right about that. After using the free driver for so long and then switching back to catalyst/crimson I immediately noticed all sorts of problems. Unfortunately I really like to play TF2 though, and the free driver has that crashing issue.

The problem might not be the driver, it might be TF2.

Check the logs and see if it might be related to libtxc_dxtn (s3tc support) in Mesa. Otherwise, try contacting the TF2 developers and see if they can help.

I know some games hiccup if S3TC support isn't available, but that list is very few in number.

I think this is going to change a bit this year for newer hardware that supports AMDGPU since it will share a lot between open and closed drivers.
The open source drivers are working really great but the closed fglrx is slow to adapt to new kernels and xorg versions but i actually believe this will be something of the past with amdgpu.
I think fglrx will also be released more often one it kicks off since amd has talked about releasing the closed linux driver as often as the windows one.
AMD are trying real hard to make the linux support better both the open and closed drivers and if you like open source drivers then there's actually no competition between nvidia and amd since amd wins big time.
Nvidia doesn't even share their non-redistributable signed firmware needed for open source support for newer cards.
If you prefer open source drivers then there's AMD and Intel i think the AMD drivers works better and is more stable but it's only my opinion and with the development that Intel throws in this might change soon.

Do you have any logs of the crash?
I think i read in an other thread that ahc_fan got an R7 250X that's an Southern Islands, Cape Verde, GCN1.0 card that isn't supported by AMDGPU it's uses radeon and radeonsi.
How do you replicate the hang?
I don't have the same hardware but i do have a card that use radeon and radeonsi in my laptop so i might try to replicate it since TF2 is free to play.
It's not my type of game so hopefully i don't need to play it to long.
Did you file an bug report?