Hi Michael
i think you should read carefully "Note 1816819 - Dual Stack support for Business Suite systems"
Is your system a "SAP NetWeaver Process Integration with Business Suite XI/ESR Content and / or PI Adapter (SWIFT, BCONS, ELSTER)" ? if yes, you can carry one with dual stack but bear in mind that for nw740 there will be no tollerance...
Regarding the split of systems I've got no idea, sorry
a
