ColorMunki bundle is a spectro, so it drifts slower than i1D3, which is a colorimeter.
ColorMunki on the other hand is quite slow and inccurate at low-light (<20%). i1D3, as i heard, is much faster.
One way is to use ColorMunki as a "reference", and profile against a cheap colorimeter. ControlCal website sell a ColorMunki+Calman+i1D2 combo for only a bit more (not sure if this is still valid). That way you get the accuracy, can profile as much as you want, and got the colorimeter fastness.
Another way is to just send your i1D3 for recalibration every once a while. How often you send depends on how picky you are and your storage/meter condition. Since no one got i1D3 for a few years, I don't know anyone can tell you how much it drift... However, I think 1-2 years is probably within the ballpark.