I reckon take it in to a garage and get it checked properly. I'd still be leaning towards your head gasket being gone. With your thermos on the whole time with the switch disconnected the temps still rised, so I wouldn't bother replacing the switch at this stage. If your thermo's full blast can't cool it you have something major going wrong.

no no, only realised for sure that the switch was gone after it heated up this time. that was when I pulled the plug on them.

ohhh all good then, easy fix.

not so easy fix ... bleed again today, unplugged thermo's so they on... still heated up. FML ... oh well ... Ill just have to drive the N/A around for a bit. no biggy.

Hmm I never had fan problems but it can't be that bad considering the coolant capacity? has this car ever had engine swap?

I wouldn't think so, I am fairly certain that I have warped / cracked head or blown head gasket. just going to park it until a few bits and pieces arrive, then I will test further, before I strip it down. If it does come down to stripping her down though I think I will get some head work done, and possibly some cams too... turn a negative into a positive.

Might even try some Cargo seal, or even Chemiweld ... as It only seems to happen under longer boost, I am fairly certain that either it be a crack, or warp, or gasket, that it would be small enough that one of these options may fix it. 
 
Any recommendations, (regarding a fix like this) anyone know of one that works well? ... a friend says Cargoseal, yet I say chemi-weld...

I sell heaps of the Cargo seal "seal up" but I would say both are a band aid fix...

this is true, usually only a "quick fix" but sometimes (and I have had it happen) it will work for years...

I wouldn't put any of that chemical fix in a bottle stuff in my MR2's cooling system. Its likely to cause some other long term harm to something else like a heater core or radiator.
 
My recommendation would be to just get it fixed properly.
 
I would try the chemical stuff in a $1000 s-box though.