I have the 12 inch green rotating mat and the Martelli rotating mat. No issues with either. I don't have the ruler you are considering. I do like the CG line though and find they are my go to ruler(s) now over other brands.
A few suggestions for you that might help with cutting issues.
Try a 60 mm cutter. I seem to have more control using the 60 vs 45 mm cutter.
Do you have grip dots on the ruler(s) that you use for cutting? They help keep the ruler in place on the fabric.
Try a cutting glove too. I find it helps to keep the ruler in place and of course it is for safety reasons too.
Thank you Paper Princess. I was looking for the vendor with those mats. I saw a demo at a quilt show and liked the concept of those mats/tables. Her furniture pieces are beautiful too.