Hi Kev, After about 6 months with the EXOS2-PMC8 and a 200DPS scope, my experience is that it is possible to get good guiding with this setup, I frequently get 0.80" total error on PHD2. ..but it is very inconsistent. Exact balance seems to be everything, and changes with the side of pier you're on, the wind conditions etc.etc. If you look at the attached pic I am using the 6 -12 camera-guide scope setup mentioned in other replies, and I've put a strengthening extra bar on top, where I've mounted my 50mm guide scope towards the rear. I'm still learning, and it's tough. I've never had a smaller profile telescope, but my impression is that the larger the profile of the telescope, the larger, heavier and more robust the mount needs to be, irrespective of weight. Especially if you don't have a dome of any sort to protect from wind effects. Newtonians are natural sails. This would all seem to be common sense that fits with the laws of physics, and I will probably eventually swap out this mount for something more meaty to use with the Newtonian, or just use it with a smaller profile scope. I now only do max 60sec exposures, and find I can eek out the most usable frames from that, I usually have to dump about 20% of the frames I shoot. I've tried longer exposures with little success. But I get pretty good results for my efforts, I attach a pic of M51 I did with this setup 2 nights ago. It's 2 hrs 38mins of LRGB monochrome all in 60sec shots. Just my two cents worth. Good luck.
Location: southern Spain
Explore Scientific EOS-2 PMC-Eight mount
Skywatcher 200DPS Newtonian telescope
ZWO 1600mm PRO monochrome camera
Orion 50mm guide scope
Oriion Starshoot guide camera
28mm 2" and 12mm 1.25" lenses.
2 and 5 x Barlows.
Huawei Android T5 Tablet
Software: Kstars / EKOS, ExploreStars Android & WIndows, Stellarium, AstroDSLR.