Glad to see another soundpro at853 stealth taper jumping on the wagon!
I have the -1 and -6, the -1 fell apart on me and sent it in for warranty repairs. I also own the 6 with the hinge so i can pop it open quickly to set volume on it, works ok i suppose. The bass filter, for me, works like it should, rolling off incredible thick midbass that always haunts rock and metal shows (perfect example: current Metallica tour). That bass is shit and can muddy up a recording without any bass rolloff quickly, imho.
I also have the same mics you picked up with hypers, oni's (never used the omni's!) and standard cards. I use the hypers all the time now and like what i hear, altho, they are a bit bright and rolloff the bass themselves...might want to take that into consideration when selecting a bass rolloff.
I taped a Neil Young show last night and there's some light static (clipping) even tho i was hitting a constant -2db on the M1 all night, so i guess this is where (i think it was nickgregory?) was talking about the soundpro at853's clipping easily due to excessive bass in a show. Just take that food for thought when taping, next show i tape i'll make sure to keep the M1 meter around -5db tops.
Enjoy taping with the at853's!