ArchiCAD version and migration is really a pain, especially when files AIN'T Back compatible! Ever wished you could just open a pln in any version.
Anyway the way our office (a small office) works is to keep all AC15-17 & for BIM, only do necessary upgrades. This also means every computer keeps 3-4 versions of AC and flexibility to work on different versions.
Ryan Wu
Desktop: DELL Vostro 460, Intel i7-2600 8GB RAM
AMD Radeon HD6670
Windows 7 Professional 64 SP1
Laptop: ASUS 56V, Intel i7 3610QM 8GB
NVIDIA GeForce GT 650M
Windows 7 Home Premium 64 SP1