RE:The total nav should be calculated by adding the ....Interesting perspective on the Premium. However, the reality for Common shareholders is that they are subordinated to the Prefs which effectively reduces the Unit NAV by $10. As such, the value of the Unit NAV is irrelant to the Common holder.
I initially used the same math that you used to calculate the NAV. I just tweaked it a bit to save time. If Middlefield changed the percentage of cash held, or changed the ratio of Prefs to Commons, your calculation would still work and I would have to tweak mine again.