Thanks for your thoughts, everyone. I guess being able to keep the 90mm f5.6 on the Wista (or probably any view camera) when folded was a bit hopeful, and I'm not so keen if there's a risk of being bellows restricted with the big rear part of the 90mm.
Although a bit heavier (but still a lot lighter than the MPP), I'm now looking at the ShenHao HZX45-IIA. Maybe not brass bits, but for me, stainless steel metalwork is much more preferable than the aluminium on the lighter ShenHaos. Also seems to have more to offer in terms of movements than the Wista. Thoughts on things like build quality, ease of adjustment and usage, etc, would be appreciated. Am I likely to encounter any movement restrictions with the 90mm?