Hi Stuart
I have and use the Sorby texturing tool set and find it extremely good I spent a day with Nick Agar using this tool on one of his Viking Sunset bowls and Nick is a master with the tool.
If you are looking to do texturing then you won't go far wrong with Sorby, but then I would say that as I stock and sell them.
However I have not used the Crown but looking on Axminster Tools I can see what George is saying the Crown is 99.00 where the Robert Sorby is 165.00
All the best
Ed