Thanks guys.
If the stands up by March, I will be dropping the 7yr olds and keeping the 6yrs til May.
The theory behind this formula is that the handicapper has deemed them to be better horses but their age should give them more scope. Extreme distance and ground will effect the young horses stamina.
Conditional jockey make more jumping errors. That said I will always go for the better chase jump jockeys and some of the more experienced conditionals are already better over fences than the journeyman pros.