"A ukulele is an instrument in its own right "

True, while they are both from the same family and familiarity with one of them will help you understand the other both have their own subtleties and different techniques, playing stills will suit each instrument differently. So, it's not necessarily a good thing to transfer everything you've learne don the uke to the guitar or vice versa.

It's the same thing with the fidlle and the mandolin. Of course, the tuning is the same and the fingering is "similar" but you still have to approach each instrument differently.... i.e. picking patterns don't always correspond to bowing(Most of the time, in fact) and ornamentation is different.