When I first went to Birks my intention was just to get the rigid blue inserts. They fitted ok into my shoes, so I decided to give them a try. I found them very helpful, the difference was instant and amazing. They are not quite as comfortable as actual Birks shoes, but almost. One minor problem - I was conscious of the feeling of the front edge of the inserts (they don't extend the full length of the foot, just the heel and arch) so I wear them with leather inner soles over them, and that helps.
The day I bought the inserts, I mooched around the Birks shop a while, and there were some Papillio at very reduced sale price, in my size, so I tried them on, and ta-daaaa!!!! Now I have 4 pairs. No money, but happy(ish) feet.
Before Birks I had been to a Scholls shop, they also do inserts and they had a chiropody adviser. Obviously they want to sell their own stuff, but the assistant I spoke to was incredibly helpful and NOT a pushy sales person at all. I bought the Birks because they felt slightly better and were much cheaper, in that order!, but Scholls were definitely worth visiting as well.