[Shiraz (Ray)]

I assume that the 15kg refers to the 3x5kg counterweights. The scopes etc will probably weigh about 10-12kg?? which is within the mount's specs (eg Bintel quote loading as Total weight: 15kgs (counterweights not included)) . It will work OK if you are careful with balance, but minimising weight in any way you can will be a good idea. Attached image (scaled 0.5) was taken some time ago with a similar scope/mount setup and shows that the HEQ5 mount can do OK with ~11kg load - there were coma and processing problems, but the mount did fairly well. If you were starting from scratch, get an NEQ6, but you have the HEQ5 and it will almost certainly be suitable for the stated task - tidy up collimation a bit and then see if there is much differential flex between the two scopes. If there is too much, get a smaller/lighter guide scope.