i looked at managewp when it first started and it had a free trial but the pricing page at the time said " ummm, we are still working that out " so i never got involved.
now i see the pricing i think its a GREAT system but the fees PER MONTH need consdiration to their benefit as I generally only update a plugin IF its a critical security alert, or a major change, i don't stuff around with 3.1111 changing to 3.1112
once you are commited and spent the time putting your sites into it then it would be hard to leave ( just like hosting and domain rego really )
especially if you are running over 200 sites, YES.... time is money but in the example of the professional 250 websites package i don't think i spend $1800 a year of my time on doing updates.
tim