I use the 200 PDS on a HEQ5 Pro unmodified and it works really well, i think it depends on the copy you get. I almost always get 0.5-0.8 RMS guiding in arc seconds and feel limited by the seeing not the mount.
While it may depend on the copy you get my local dealer actually recommends this combination for Astrophotography (many dealers sell them as a pair for imaging) and i know others who don't have any issues with this setup.
My Setup / Relevant Payload:
ZWO ASI 533 MC Pro
ZWO EAF Electronic Focuser
ZWO Off Axis Guider
ZWO ASI 120 MM Mini Guide Camera
Explore Scientific 2" HR Coma Corrector
Total: 10.5 kg
So i would say, if you can comfortably afford the EQ6 or another mount with more payload capacity why not, but if the HEQ5 is what you can afford i would not worry about using it with the 200 PDS.
This guy takes fantastic images and even uses a 10" f/4 on the HEQ5:
https://www.astrobin.com/users/sky-watcher/Another thing to consider is that with todays sensor technology and the relatively fast optics of the 200 PDS the read noise is negligible when doing 60 second subs even in dark skies if you are doing broadband imaging.