Have the GT, lower dog bones, lower seat position and the lower seat... i find it slightly higher than my MT09, so I guess about 815mm without measuring it.
Comfort wise i think its fine, but I never rode with the standard one..
Thanks , it seems that the low seat option is an option, as yours has dog bone lowering it may be difficult to calculate how much lower the accessory seat height is on a bike without dof bones fitted
I reckon, from what you say that the accessory low seat is about 20 mm lower than standard
I have contacted Yamaha UK and asked this question but they replied that they didn't know ! and I should ask a dealer