Thanks for the info-I'm going to try it this week.I've seen WJs homepage but am not on the mailing list.The pro grain filter(actually there are two:course and medium that come in one package)is made by sunpack,I believe but is availible from B&H photo-the only place I've seen it.They go inside the camera between the shutter and the film and depending upon which one you use you get acertain amount of grain on your negs,prints.The problems are,dust-If any dust,even the smallest particle is on it then the dust spot will appear on every photo in the roll so unless you use a black bag to remove it your also geting grain with each photo.Also it would appear,at least with IR film(I did not use them with regular bw film)that they are very inforgiving of exposure.The more you overexpose the neg-well lets just say it disapates the entire image,so you need to be exact with exposure.The only other issue is not poking it through the shutter(a warning on the label)but I saw no real concern.
I would think it easier to add the pseudo grain when making the print, as well you would have an unaltered neg to use in other ways too.
WJ recommends a polyester filter between the rails for opaque filters to uncomplicate the shooting and speed up the process. You can see to focus and shoot immediately and you can use any lens you have without having to buy new filters or adapt one size to another. Makes a big difference to him as he takes his camera along on backpack ski trips where fiddling with a filter while shooting can be a very big chore. Its really valuable for wide angle lenses that tend to vignette with any filter in the way.
That said I don't have that because I haven't figured out how to do it with a Bronica SQAi. I will sooner or later but now I get satisfactory results with a 29 red filter.
After my first two attempts(one for each grain filter)I gave up-realizing as you've pointed out that there are better ways,but hey I'll give most anything a chance at least once.I'll have to look into the poly filter-it would be easier-it is a bear screwing on a filter with fingerless gloves in ten degree weather.I find the 29 red to be good in most situations also,but with maco 820c and konica if the weather is overcast or cloudy with little to no sun I find the best negs come from the 89b.Actually in my opinion its when konica750 comes into its own.