berger has his bike on trail gearing and so perhaps would you - AS BOUGHT. but if you would like to try a 14 x 51 you can crawl along without labouring the engine.
there are some who have had coolant spit issues in the states but - as i'm aware - nowhere else in the world.
these things can be overcome and it isn't an issue for all riders. some use 'ice', some fit a fan, some bleed the system, another found a mod to do to the cap itself.
it's not usually a big issue on the smaller bikes (400-450).
regards
Taffy