If its a £20-£25 increase thats around 6% on £300/1000 28g cartridge ( and that £300 is hard to find ) not as much as some feared.
Recoil is subjective / unique to each individual and there are lots of variables, me Im 60+, 6ft, sub 13st with a sub 8lb MK38 and bar a few 28gm White Golds which I did think kicked a bit, will happily use any cartridge, those “obnoxious” Hull Sovereigns I found very pleasant to use.
Have some B&Ps in 24g at mo, cant say Ive noticed any noticeable difference recoil wise and in 7.5 shot size the breaks, even from I seemed decent enough.
As we can still use 28g in competition most of us will still do so, if load gets pushed down then at 24 or even 21g most of us just simply get on with it and hardly notice any difference.
As for cost, any drop in load wont offer a comparable drop in price of any cartridge, the cost of the load element of cartridge yes or rather will be / is for the manufacturer, how much or if all that filters through lord knows.
The sellers of cartridges, if the margin is £50/1000 I can see why its not really attractive proposition for a start up, the sheer volume you need to stock, even with a single brand ties up a lot of cash, let alone all the other costs needed for running a selling cartridge business.