I never had heater boxes on my 2,110 because I didn’t think I needed heat AND the larger-tube boxes were something like $600 USD each! Lived without heat for 15 years and thought it was OK, but had a home in a warm state and drove there all winter. To avoid $1,200 in heater boxes I spent $400K for a house instead! 
Danny’s post of the gas heater farther up this thread is right on. For about the cost of a pair of larger heater boxes you can get more reliable heat than you’ll ever need AND with true working defrosters. I have an Eberspascher BN2 that I have throttled back to about 25% of full output and it is perfect for cockpit heat down to about 35°F outside. If I were to turn it up it would drive me out.
From what I learned on several gas heater forums as well as from some truck heater techs I spoke with, all of the inexpensive Chinese copies of Webasto, Eberspacher and others are poor quality and should be avoided. Like buying Speedster parts, you may like the low, low price, but you won’t like the product when it dies!
Lastly, any heat you can get, whether from heater boxes or a gas or electric heater, will be wasted if you don’t find and eliminate any cockpit air leaks (and there are usually lots). If I could totally seal my cockpit (almost impossible on a CMC) I could get by with a lot less heat so I compensate by making more heat than I should need - That works.