I've got Excel 2016 suite for my 2014 rMBP with Office365 and have been dealing with some big spreadsheets with 10,000s of cells, each with conditional sum formulas. I've found that the mac version just cannot cope with spreadsheets with this number of calculations, taking upto 5 minutes to load, continually pausing with "calculating" at the bottom and crashing at times. I've opened the same files on windows 10 and despite a few waits for calculations to be performed there haven't been any major problems. Have others found similar problems with excel 2016, and do you think it will get more stable? It's a real shame it isn't more robust. The look and feel is comparable with W10 and for smaller spreadsheets I've found it excellent.