mel,
not really.. i dun really find BECO more bulky per say. I feel ERGO is actually bulkier, but the padding is great esp with heavier kids. Not that i want to confuse u, but you can also consider ERGO if you are looking for a carrier.
For me, I like the pikkolo because of its versatility, particularly the adjustable crotch area. Plus its cross back carry, which provides great support. It's fairly lightweight although it has abit more structure than the BECO, which has a softer overall feel to it.
i think it boils down to personal preference..