While we do not have everything in a single rack space...we do all run direct and use IEM's. We pretty much all have our own rigs in a separate rack. Set up is fairly quick (full pa/lights, instruments, soundcheck can be done in an hour if we push it, usually closer to 90 minutes on average though with the mandatory union beer breaks, lol) however there are some things that I've noticed the 4 years we have been doing this.
1) it makes for a very 'clean' FOH sound...sound guys love it...I think the 'atmostphere' of the gig suffers as a result though. The PA sound is so clear (our sound guy is a audio nut and runs a pretty good mix/sound), that there is no vibe/atmosphere or feel when you get within a certain distance of the stage. There is no amp sound, only drums and vocals...I think that reduces the feel for the audience, especially those that wanna dance. Now we get dancing crowds and they dont come within 20 feet of the stage and I think its a subconscious decision because of the sound is and where it sounds best. Years ago before IEM's in previous bands we would have people right up front as there was guitar/bass/drums and wedges to carry the sound.
2) to combat #1...you can have a sound guy run a fill monitor or such on stage to help with that...however, depending on your sound situation that isn't always feasible...which leads to #3
3) we have our own dedicated sound guy that we have used for the 4 years this band has been around. Uses the Behringer X32 board so all mixes, monitor and FOH, are saved. I've resorted to running IEM's with a floor wedge and controlling the mix of both. My IEM's have my vocals and a touch of guitar, the wedge has the rest of the stuff...and I pull my left/inside ear bud out and work off both. This works great for me.