In a desperate attempt to actually answer the OP's question, we moved from a pair of RCFs to a MarkAudio column-based system about 18 months ago. This was then a 4-piece covers band doing 50s-80s music, and we were really keen to start routing the entire band through the PA to keep on-stage volumes acceptable.
At the time, the range of column systems out there was really pretty limited. We felt that the MarkAudio came closest to what we wanted. Judging by what we saw at NAMM last week the market has since expanded dramatically and the choice is way wider.
Will these systems do what a pair of Mackies or RCFs will do? Yup, absolutely, plus they bring other advantages.
1. On narrow stages or platforms a pair of RCFs at head height will block out a surprising amount of the view of the band. Column systems make the stage area feel wide open and spacious.
2. Mackies and RCFs have the amp inside the cab (well ... duh!) which means that at each gig a pair of 50lb units has to be lifted to head height and placed on a pole. Column-based systems have almost all the weight concentrated in the sub-woofer sitting on the floor. Not only is this good for your back, but it means that the entire unit is far more stable and punter-proof.
3. At many pub gigs the splayed tripod feet of the PA poles are a significant trip hazard, especially as the punters get drunker. A bloody great 2x10 sub-woofer is much less likely to trip up a dancer. On t'other hand, it's really very difficult to put your pint of lager on a PA tripod ...
4. If called upon to play a much larger gig than usual, or maybe an outdoor gig, and assuming that you kept your old pole-mounted PA, it's very easy to combine the two different types of system since they occupy very different spaces physically.