I don't think the Mopho keyboard could ever be a regret. Granted the poly chaining process is a bit sloppy, often requiring 2-4 separate channels on a mixer just to get the levels right, but it is a keyboard, it's analog, has aftertouch, and it's $700.00.
If I had a budget to allow for an analog speciality piece, this would be on my short list, with the intent to purchase the Tetra down the road. Plus it looks compact and killer.
I will throw one other choice your way. The DSI MEK PE with the DSI case is what I would take first of all.
I owned a PEK for a while and miss it extremely.
I just wish the MEK's PE version had the Tetra/PO8 knobs, but oh well it is still great.