I have not read every post on this thread, blame it on a head-cold.
When ever you make a major change and on a racer level it kills a popular class don't be surprised with a backlash.
The 27t motors are a standard that have been around for years. If you goto any, I mean any RC car track, there is always a 27t motor class. I have not been to Europe racing, this is the way it is in the states and Canada.
Changing from 27t to 19t will kill interest in a class and in some cases the hobby for certain people. I know in Batavia when the 27t rebuildables came out, we decided to eliminate the tabbed motors in exchange for the rebuildables. We did lose interest, in the long run it benefitted the class, making it easier to tech and check for cheats. One major disappointment to that change was some guys had a stock-pile of 27t motors... myself included.
If the 27t class had only 4 or 5 racers in it at a given race, then either drop it in exchange for a better class that generates interest. We kept P Tunnel around as long as we could, due to lack of support we had to drop it for a better class that generated more interest.
This year in Batavia we will have a 27t (we have always had) and 19t (which is new in Batavia) N mono class. Something new to try, the 19t is in exchange for N Mono Mod. We are not replacing N Mono mod just offering a different class for our venue.
In so many words I would just either offer or not offer a class instead of flat out doing a major change to it. Usually major changes cannot be reversed and can alienate new boaters who like a given class.
Jeff
