About two weeks ago, the VARIDESK Pro Plus 30 arrived and being able to alternate between standing and sitting has made a big difference in how I feel and how much energy I have at the end of the day. It is supporting a 27" iMac and I have no stability issue with it even with the risers completely extended. I am 6'5 and fully extended works best for me. There are also multiple locked heights between the minimum and full elevation positions.