For me the trouble spots or extra labor with my kegging system have been:
1) nailing down length for my liquid (beer) lines to the taps, but there are plenty of calculators for that. I do vary line length depending on carbonation level of my brews, so switching lines out occasionally is a bit of extra work.
2) chasing down the occasional leak - it really sucks to open the keg fridge and discover that I've released a bottle full of CO2 into the atmosphere. I imagine this doesn't happen to everyone if you have assembled your keg system well, but I've occasionally run into it due to having switched out parts or having a keg that didn't seal completely unbeknownst to me.
3) cleaning keg lines - this should be part of routine maintenance but is a task that should be taken into account when considering moving to a keg system.
This being said, moving from bottling to kegging was overall a pleasure and I've never regretted it. There's something I find satisfying about drawing a glass of beer from my own tap.
And yes, I'm wondering if there's confusion here between carbon dioxide (CO2) and carbon monoxide (CO), the latter being poisonous and something to be avoided, but never part of beer serving.