i don't see why not. i did. that's how i got my birkins and kellys. if i sense SAs are unhelpful then i find one that is. i don't believe in all this relationship building and buying other things to get on the list. i was never on any list and never bought items i didn't want but happened to have connected with a few wonderful SAs.
you just need to be prepared for unpleasant snooty SAs who may make you feel small with their cold and curt responses, of which i have met a few in London. i don't let them affect me - it is a reflection of their poor manners and i have commented to their store managers when the opportunity arises. saying that there are a lot of helpful and wonderful SAs around and i have also complimented them to their store managers as well.