Ibussell :
Burna :
Certainly, feeling a difference between a BP/W and a jacket-style BCD depends on the diver, the amount of lead he (or she) needs, the amount of lead he (or she) uses, and where he (or she) puts that lead.
But given the weight of a SS BP (about 5 pounds) there are ways to obtain the same trim by putting your weights in different locations, eg in the pockets of your BCD. And an Alu BP, much more "travel-friendly", is too light for having any significant influence on weight distribution.
Regarding trim, I (and all my fellows with similar experience) don't feel much difference between my BP/Ws and my jacket-style BCDs for recreational depths in warm water, where I use 2 to 4 pounds of lead with a 3 mm full wetsuit, an Al80 tank and a jacket-style BCD.
The only thing I miss (sometimes) when diving my jacket-style BCDs is the crotch-strap.