Limiter?

It will make your overall mix less dynamic and compress everything so that you might not get the full depth of jams and thus wouldn't be able to interact with subtleties. This is especially so because generally, the master is clipping when you ahve a full room jamming. I've thought about doing it myself but never went for it for this reason. Definitely worth trying out, couldn't hurt to try.

Try it at a setting of 0.0, if it's at -2 and the mix is steady at 0.0 or even -1.0 that's where you will run into compression. If the master surpasses 0.0 it's already clipping anyways and you will get saturation. Saturation or compression, you decide. Worth noting that the autosong on both ninbot and ninjam both implement limiters (not sure of the specifics) so by listening to a jam where you know levels are above normal you can get an idea of what it'd sound like if you threw a limiter on your master.

My signal path has two limiters - one to add oomph to my drums (which have an average level somewhere below -20dB) and one to prevent any subsequent effects (e.g. reverb) pushing the level too hard. The first gets adjusted depending on the session. The second stays at 0dB and lives on the master track, as you're suggesting. I use Kjaerhus Classic Compressor for both.

Nicely explained Chazz. :)

Yeah NINJAM's auto records does limit pretty good, its almost like an auto gain than a limiter its so clean sounding.
When Chazz says saturation and less dynamics this will basically be like putting thin layers of foam over you speakers until you can't hear the clarity, then trying to turn up the volume to compensate which wouldn't make more audio clarity but would make the dynamic-less sound louder and more gained sounding.

If you use a limiter it would be better to keep lower so there's less chance of being limited then use some auto level to bring the volume up. This would keep the dynamics more intact.
The limiter would be there just in case and the auto leveler will reduce if anything hits it higher than set level which could be say -6db.
Also put it in as an fx on a tack and not master, or send all your tracks to 1 track, add the fx here then send on to Master.
An EQ maybe needed at the end to clean the sound up to your liking but don't over gain the EQ settings or your push the signal back over 0db. So if one band is set to +6db then drop the EQ's master gain by -6db to -7db or pull all bands down by 6db.

If I got anything incorrect here Chazz could correct it, his good at mastering sound, I've asked for many a tip from him in the past. ;)

So much to learn... thanks guys.