First I will say I think the BPS is as well designed and built as any. I had three and they never bobbled once. But I have also had 6 Wingmasters, and I do not think they are even a hair better than those.
1- They are heavy compared to the competition. I went so far as to machine down a 10 gauge because it was sooooo overbuilt.
2- I do not like having to load thru the magazine rather than throwing the shell in the side for a quick follow up shot.
3- They feel like they have a longer reach to the fore end to a lot of people
4- For a long time they were more expensive than a Wingmaster, and they still are more expensive than a Mossberg 500 or an Express.
I could care less where a gun throws the empty or where the safety is as long as it works.