The biggest argument in favor of MDI as opposed to pumping is that there are very few failure points with the former and very, very many with the latter. Kind of an inherent problem with any advanced technology. In practice, what it means is that you have to balance the advantages of Pump + CGM against the occasional inconvenience–or at times, the sheer head-banging aggravation–of keeping the whole Rube Goldbergian thing running. For me the line was crossed with the 670G, which layered a whole new set of failure points onto a system that was already replete with same, thus ramping up the aggravation factor while falling short of the promised advantages–supposedly a pump that would be so smart it would do a better job of managing my BG than I could. Wrong.
But I know other T1s who draw the line at changing from MDI to a pump–they’re used to it, getting decent results, and it’s simple: you put the needle on the pen, click to your number, stick it in a nice fatty spot, sppppt! and you’re done. I can sympathize–my own transition to pumping had me close to throwing the thing against the wall many times (my very first set of reservoirs ended up being from a batch that was eventually recalled, speaking of failure points). But I did go back to my pens for a few days a year ago when my pump broke–going into a weekend of course–and that was enough to convince me I didn’t want to stick with MDI any longer than I had to. I do think that over all, CGM is a much simpler and therefore robust technology. If I had to choose between giving up my pump or my CGM, I’d definitely stick with my CGM.