> How much of this was down to practicality, though? Being able to pick and choose the best gear from each side?

I'm not an expert on cold war Finland, but my understanding is that Finland was threading a very fine needle between not provoking the USSR (see Prague 1968) while still maintaining relations with the West in order to not be seen as being part of the Soviet sphere of influence (which, again, can be seen as form of insurance against a Soviet annexation). Foreign trade, and in particular major arms deals, were VERY politicised, and I'd imagine there would be a need for very strong differences in military/technical capabilities to override the political considerations in any particular deal.

Sure, my point is that this also presents a rare opportunity. Countries that were fully aligned one way or the other wouldn’t be able to get any equipment from the other side, even if it was a better fit for their requirements.