Observation about HX designs

I had my Vitodens 100 cleaned out for the first time recently, after 16 months of use. There was a small amount of combustion debris (maybe 1/2 teaspoon) that looked like coffee grounds inside, that the technician cleaned out, along with cleaning the condensate trap, doing a combustion test, etc.



It occurs to me that the fire tube HX design as in Triangle, Lochinvar, may in this respect be superior to the radial design as in Viessmann, since in the fire tube, the "coffee grounds" will simply flush out of the HX as the condensate drips down.