In an attempt to answer whether the lazy method of SMBC yields a comparable product:

(Note: all measurements in ounces are by weight, not fluid ounces.)

I made two batches, one following the traditional method: https://fromscratchsf.wordpress.com/2011/03/08/tutorial-swiss-meringue-buttercream/

One lazy: http://www.cakepaperparty.com/2014/04/foolproof-swiss-meringue-buttercream/

I heated 7 oz of egg whites with 9 oz of sugar to 160. When it was finished I had 14 oz of the sugar/egg mix. Not quite sure where those other 2 oz went! It doesn't seem like I'd lose water in the whites to evaporation since they were only heated to 160. Weird. 

I beat half of them to stiff whites, added 8 oz of butter, beat it forever on low, and added a tablespoon of vanilla. 

For the lazy batch I beat 8 oz of butter, slowly added the second egg/sugar mixture, then beat on high for a couple of minutes and added a tablespoon of vanilla.

Yields:

The classic method which you would expect to have a higher volume because of the beaten whites yielded 14 oz or 2 cups

The lazy method yielded 15 oz (so obviously my split wasn't exactly in half!) or 2.5 cups. 

Dividing it out that actually translates to slightly -more- volume in the lazy method but I think that's probably a measuring error and consider them virtually equivalent.

Taste: both delicious.

Appearance: the classic method appears slightly smoother. This isn't surprising since this method involves a lot more beating on low. Now that they're both done I'm going to throw it back in the mixer on low for a while to see if it smooths out like the classic.

The finished product is going to be a chocolate mud cake. Three layers filled with nutella buttercream frosted with caramel buttercream.

My kids are fully in favor of my science project. :D

AHey, awesome! Definitely interested to see how this turns out.

very interesting.  there's more than one way to skin a cat.

AThe extra beating (on low) of the lazy SMBC left it comparably smooth to the regular one, IMO. Especially after adding the chocolate (I was out of Nutella!) and caramel. I couldn't tell a difference in the finished products other than the flavor.

I'd love it if someone more experienced and discriminating *cough*AZCouture*cough* would try the same experiment and report back.