I've owned: 700RBII, 1001RBII, mbfusion, traynor yba200, TC classic 450, peavey max450, Ashdown ctm100, ashdown originAL 300.
My favourite without doubt is the mbfusion.
Just trying to work this out this morning myself.
On the line 6 M series (5, 9,13) the voice box effect gets pretty close IMO.
It also has quite a lot of control for fine tuning- which most auto wahs and bassballs style pedals don't.