Just wanted to share the solution to my 8" Meade LX200 DEC guiding issues with the OAG, in case it's useful to someone else in the future:
1. The scope was ever so slightly out of balance in DEC, with a tendency for the corrector plate to drift to the South. I corrected this, and made it so the scope (corrector plate end) was ever so slightly imbalanced towards the North.
2. I disabled all anti-backlash settings in the hand controller (RA & DEC). I did this by setting the percentages to 0%
3. I enabled the DEC backlash option in the PHD2 guide settings.
4. I still wasn't happy with the recommended 200 calibration step size, so I manually entered 400. This worked fine.
The mount happily moved in RA & DEC, and after a bit of fiddling with the guide settings I was able to achieve the attached guiding graph. Pretty happy with the star plot as well.
Still a bit of movement in RA that I need to sort out, however, I shot a 600sec ISO800 exposure on the Eagle Nebula (Canon 600D DSLR) and the stars look alright
The only thing I wasn't sure of was my Tot RMS error. It seems a tad high. However, I was using a guide scope previously and the RMS error there was always below 1.
I wonder if the image scale might have changed due to the OAG though? If it has, it might be distorting the figures?
Cheers, Evan