For your examples on vigor and precocity, I would say yes they do stack. Of course the site and growing conditions have a large influence as well. I have no idea in your situation which would be best. Perhaps you can judge by nearby trees. If they are vigorous, double up on vigor control.

Just be aware that lack of vigor can be as aggravating as too much.

I am more concerned with lack of vigor...not a patient one, and like I said I don't mind summer pruning still the tree is right next to the house and I don't want it getting out of control.
Unfortuantly I can't go by nearby trees at least in terms of seckel. The soil on the site are marginal...a lot of hardpan got mixed in with the backfill. I plan to amend the planting site substantialy with top soil....in some ways it will be a tree in a big pot which as I know fruitnut can tell me (I lurk a lot) will have some dwarfing effect as well. This tree is really more about landscaping and playing with the espalier form than fruit...but It gets great sun and that can be a precious commodity for us!.

Earlier today I read a note from university of oregon suggesting BET might be well suited to seckel since it appears in increase fruit size and help against excessive fruit set.....more information to muddy the choices.

Bet is not widely used in the northeast because it is not considered adequately hardy- it is also just too vigorous for your purpose, I think. I like it for Asians in my somewhat warmer southeastern NY, but Asians are born to bear fruit.

I find the OHXF root stocks to be pretty sluggish in getting established and think you'd probably be best off with the seedling rootstock. Seckel is pretty cooperative and fruits relatively young so I think it will do fine in your situation.

Thanks for the input harvestman, I was zeroing in on that decision as I learned a bit more.