RE:Has ENS been losing ENB shares due to option exerciseObscure...assuming you mean an 8% discount not premium...
As for your other points, frankly, IMO, you are overthinking all this. The impression that I have from reading the Middlefield literature is that covered options are small part of their strategy. When you combine this with the fact that on average only about 7% of all call options are actually exercised and for Middlefield their call options might not even be assigned in that 7%. So when you put all this together, the options part of this is most likely insignificant. Plus, if Middlefield was selling call options in a rising market they would most likely be selling out of the money options and get a capital gain plus the revenue from the sale if they were actually exercised.
As for strategy in my case, I have mentioned before that I don't have a full position. I like the fact that it is trading at a discount to NAV for the reasons I outlined here many times. For me, a great result would be for the SP of ENB go down x dividend and by the historical way (ie more than the dividend) and the SP of ENS follows suit cause people don't really understand how things work and then I pounce. If it doesn't happen then oh well and I will bide my time and look at other targets.