Ken,
In answer to part of your questions, I do not think this would be specifically a reason to go out and buy the T4, but I do think if one had already bought it (for portability purchases), then one would already have the other shaft, water tray, etc. to try.
I view this as a way to expand stone use, and for special projects (like the cleavers which has been mentioned).
Also, what do you consider "about the same"? Is 1cm about the same?
In answer to part of your questions, I do not think this would be specifically a reason to go out and buy the T4, but I do think if one had already bought it (for portability purchases), then one would already have the other shaft, water tray, etc. to try.
I view this as a way to expand stone use, and for special projects (like the cleavers which has been mentioned).
Also, what do you consider "about the same"? Is 1cm about the same?