Hi,
I have recently started to play the tin whistle and there are strong symptoms of WhOA showing yet.
Now my question:
How can a good Generation be recognized? What are the differences?
Thanks for your inputs,
brotherwind
If it sounds good, it is good. 
I haven’t bought a new one recently, but my favorite Generation whistles are my D with a head transplant, and my C and Bb whistles with the Mack Hoover blacktop fipple.
I don’t remember what whistle I robbed to transplant, but it is green and slightly too large for the tube. A little bit of beeswax scrubbed onto the tube where the fipple fits makes a nice, airtight fit while still letting it be tunable with a little warming in the hands.
My C and Bb fipples that came with the whistles sound good too, but I broke the Bb fipple. Some waxed nylon thread (dental floss) wrapped around the outside of the straight part where it goes over the tube, then scrubbed with beeswax and polished (use something round and smooth, I use scrap arundo donax) to melt the wax into the thread fixed it up nicely.
Lots of people report that the C fipple breaks when they attempt to remove them, BTW, but it can be repaired unless you crumble it getting it off.
I don’t believe that the company that I robbed the fipple from is still in business, though, but you can try fipples from different whistles and see how they perform.
Tuning Tin Whistles: Hyperthermic Adhesion Removal; Lubricants; Shaft Reduction Methods Explained