Quick update to say I pulled the trigger on the Thinline Godin. It's new, coming from the States and even with delivery and taxes will be £300 cheaper than the best price I could find in the UK!
I had a block that was non-magnetic so it wasn't steel. not sure what it was but it sounded good, only after researching did i find out it didn't have a steel block and I added one. I did notice a bit of a brigther sound, but nothing drastic and it didn't change the voice of the guitar too much but it was an improvent to my ears