Very fond of the Triumphs, and the TR6 is probably my favourite.
I had a Spitfire as well, MkIII with the 1300cc engine. It was slow but I wouldn't say dangerously so. Had a lot of good times in that thing - even drove it to the snow country to go skiing, driving for 10 hours at 5,000 rpm because of the low gearing. Nearly had industrial deafness when we arrived
The basic design and layout was good but it was let down by engineering weaknesses - replaced the dif twice; had the gearbox out twice; new generator, water pump, pressure plate, ring gear etc. At least it was mostly easy to work on so the cost was for parts only.
Must say it was driven hard though - redlined in every gear almost every time and the internals of the engine stayed sound.