Hello,
Forgive me if this has been mentioned before, but are there differences between the brass bodied and nickel bodied whistles made by generation.
I was in a music shop today and it seems to me that the nickle bodied instruments seem to be a bit more playable, has anyone else noticed something similar.
It is strictly a matter of personal preference. I have good examples of both red and blue tops. Some might say the nickel bodies are more slippery. Some say the brass bodies are more trad sounding. There is a lot of mythology surrounding the differences. But … the green tops are the best. 
Maybe someone will alert you when one is being auctioned on eBay.
Feadoggie
This could as well have been the notorious variations in quality of Generations.
I don’t think there’s any difference other than optic and haptic.
Edit after x-posting w/ Feadoggie…
The blue tops also have a brass tube, however it is nickel plated.
Most Gens are fine right out of the box, some of them exceptionally so. When I teach classes, I usually supply green top Gens. My two favourite Generations are chewed bluetops popped on brass bodies in D and a Bb. I wouldn’t trade them for “improved” ones, I can say with confidence.
If one gen is more playable than another depends on the head.
And as others have said, they vary soooooo much.
That said, I like the look and feel of green heads on brass bodies.
But, gens are my least favorite of the low price whistles.
Even so, I buy cheapies when ever I see them.
Like buying loto tickets, you never know when when you will
get a winner.
Really, what difference the color that goes into the mold?
Molds wear out and get outdated, flaws can be anticipated.
Quality controls use a small percent of a run.
Different colors make the question fun,
To toss another (fea) dog into the fight,
When it’s all said and done the answer isn’t black and white
It is sometimes shades of grey. (I sorta think it’s white that makes the day.)
that’s just my toot sense
PS
Nickel does stay shiny longer and does cover the identity crisis of new vs old.
I don’t know if there’s really much difference, but when I started playing in the 1970s all the good players I saw were playing the brass bodied Generations, usually with red tops, but occasionally with blue tops (the player had switched tops at some point).
I heard it said many times back then that the brass bodied Gens sounded better, more full, more round, that the nickel plating dulled the tone. Whether it was true or not, many players believed it.
Generations were the only D whistles available at that time. Green tops, tan tops, black tops, etc hadn’t come out, they were always either red or blue.
The really cool-looking whistles played by the veteran players then had all the lacquer worn off, label long gone, and tape or string binding the cracked head together.
Like this
One thing for sure, it’s much easier to remove the tops from the nickel-plated Gens! The lacquer on the brass ones seems to fuse with the glue and they’re the very devil to get off sometimes.
I bought a great-playing redtop Gen C and I could never get that top off! The boiling water thing till the plastic nearly melted and it was still fused onto the body.
Interesting. I have a red-top D and never had trouble steaming the top off, just for tuning (I didn’t tweak).
My C and Bb are blue-top. Same lack of trouble.
Just throw them into a bigger tube, the force moves the head up so it won’t crack. But it will break anything that makes the head stick to the tube. It managed to release, without damage, the head of my first whistle, a red top E flat after refusing to budge for forty years.
The nickel/blue ones are the brighter ones but only by a small margin.
Or maybe red AND blue on brass…
http://www.youtube.com/watch?v=nAFTIzH3Ds0
The real question is which hand goes on top?
Someone has to acknowledge the (fea)doggerel – nice Mack.
Better yet… red, white, and blue and please use both hands while playing!
Dang that YouTube playing is sweet air.