Hi Jim,
I've done a lot of all-in live playing "one room" upright bass recording and here are my experiences. These include traditional jazz sessions, "americana" sessions, and sometimes flat out chaos.
I have personally played many big band shows as an upright player and have my own preferences for dynamics in those (kind of similar to the "one room") situations.
At the bridge position, of the dynamics you've mentioned, I would rank them in the following order: RE20, 441... tied for first place. Then the SM57 (because you can get it closer), SM7, M201. I don't have experience with the 421 on acoustic bass. The M201 is absolutely positively *not* the mic for this application in my experience. The low gain and proximity boost of that mic make for a lethal combination with acoustic bass. (Aside: I love the M201 for many other applications though)
The RE20 and 441 have the best balance of "condenser-like" properties with some rejection. The RE20 bleeds more but it's a tolerable bleed. As a player, I'm content when I see these mics on stage.
The SM57 and SM7 are tighter but tend to make the upright sound very muddy and indistinct, without attack, without tone. Post-EQing of the SM's only makes matters worse.
Here's where taste, experience, etc., etc. may diverge.... I'll forge ahead anyways.
Bridge position has not been successful for me. Everyone seems to do it and my ears just can't accept it. So I started experimenting at home and on some more casual sessions with friends.
After many attempts at multi-micing acoustic bass (bridge and neck) I have discovered a single mic technique that has worked well for my bass and the others I have recorded in "one room" situations.
Use one and only one good condenser mic, even if there is a drummer in the room. No dynamics allowed. My options are a Gefell UM70s, Shure KSM44, Shure KSM32 and I prefer them in that order. Use in cardioid. Bring the mic in from the G-string side and get it close (within 3 inches) of the point of contact where the particular player attacks the G-string. This will be somewhere near the bottom of the fingerboard.
I usually engage the pad if going into a good preamp and use the low-end roll off if the bass is particularly boomy. My bass is a bit delicate in the low end so it's flat all the way down for me.
Get the bass player in position so that the null of the cardioid is pointing towards the loudest HF source in the room, usually the drums. That tends to work well because it allows the bass player to face the drums.
With this single mic technique I've found that I do not need to baffle off the bass. Everyone is happier because they can hear the bass acoustically and there's less recording "stuff" around.
The bass players are happy because this position captures much of the nuance and attack from the right hand without sacrificing any low end.
I can post an MP3 of a rough session I did yesterday and you can see what you think.