Here is a pic of the rig I used on NYE, at an outdoor gig (3 - 5 thousand pax I think probably 10K) and at a couple of 7 - 8 piece band indoor shows (100 -200 pax).
The rack has a Demeter, a Klark Teknik Parametric EQ, a TAPCO crossover (2 Band), and a pair of Carver PM300 power amps running bridged. My pedalboard is stowed above the speaker stack which is a 'Nearful' 1 X 12 three way, viz. similar to Fearful, and a 1X18 sub - pic taken after soundcheck. I acquired the 1X18 subs as a pair, as part of a deal otherwise I would have rolled my own. It works well, is crossed at 100hz, and takes the whack out of the 1X12 so it sounds cleaner as it doesn't have to cover that low end. There were good outdoor pro quality subs that NYE, so in truth the 1X18 was overkill, as all I needed was really a good IEM, but I wasn't using IEMs that night.
The Tapco was a cheap used beat up one I acquired to use as a speaker sim in the studio, and I used to use a DBX crossover, which lives now in another rack. I like the TAPCO because it has a switch to turn it off/on. The DBX doesn't, and if someone else shuts down power to your rig or if you forget to shut the power amps off first, you can get an almighty thump that would blow the speakers.
Used the same rig for a 7 piece band in a club, and it is overkill there but the subs in that club are crap. BUT, as a personal monitor, it is much cleaner particularly if I am slapping the bass. The 1X12 is good but it gets strained - not that it can't take the power, but it is sonically not as clean. If I gig in trio or quartet, I am happy to have the 1X12 on its own, but sonically with the 1X18 as sub, it sounds fantastic as a four way system.
In my rehearsal studio in sounds fantastic. I sold those subs as I have moved continents (back in UK now!), but I will rebuild some subs when I get the chance. Even made a profit on them - though they were no name 1X18s, had a pair. As a four way bass audio monitor ( 1X 12 three way, and 1X18 bottom) nothing beats it, notwithstanding the overkill. It makes my playing less strained, the notes are not distorted, and I can hear myself well. The 1X12 on its own does not do the lows as well. I have also used a vertical array of 4 X 5" as a top to the 1X18 at rehearsal, and I run the cross at 200-250hz. Sounds good, and I would gig with that.
That said, I would rather use IEMs at a gig, because as great as it sounds, once the crowd turns up it's a crapshoot - it will not sound the same as soundcheck. The IEMs give me the same monitoring sonics as at soundcheck; and I don't get frustrated trying to hear myself, or hear the tone I want to hear.