I have built this plane with the rudder servo down the tail, for a push rod onto the rudder.
Are you saying this will cause some hunting problems?
No--just as long as there's no slop in the linkage.
If I go with the JR's, is 1100 ma battery still ok?
Should be.
What about progaming the JR's like the Hitecs can be with thier programmer.
Can this be done on JR, so like I can reverse one elevator servo?
Not sure re Hitec programer whether or not it works with other-make servos.
The higher -end JR Txs have specific programs for dual elevator(And everything else dual),as no doubt do Futaba.
Or the JR or Futaba Matchbox is another electronic solution.
Or of course if there's enough room, with a lot of care in the installation, (and some luck with a matching servo pair),if the servos are in the fus sides, you can simply have the two servo arms facing opposite ways(one up, one down)on the same channel with a Y lead.