Heat Exchangers vs Propane Heaters

I'm in a dilemma, I have only used propane heater and know that they do heat water very well but do require the yearly maintenance of taking them off the truck to clean the coils from all the soot that builds around the coils, this is very noticeable because heat starts to decrease, the one I had was a 250,000 BTU's and very heavy and difficult to remove, but once this was done and an acid rinse run through the system, it would be like new again and also as described in my other question on installation topic, a hole has to be made on the roof of the van in order to vent the exhaust of the burner directly to the outside. How does the propane heater stack up against units with a heat exchanger, I am sure that these need to be cleaned at least once a year also as the carbon buildup must start decreasing its ability to heat the water properly and what about its longevity, I'd like to have input from experienced operators as to which system would be a better choice.

I only had one other heat system and that was an oil fired Pro Chem unit years ago. I have had HX systems since they came out from Pro Chem. I didn't even consider propane back then when purchasing a new unit. I didn't like the idea of the igniting the burner before each job?  That's if my memory serves me right?

They were simply a PITA?

MR. STEAMER wrote: I personally thing  that they both need maintenance.  It all depends on your setup...   if you don't have a chemical feed and you run soap through the unit...you'll find that the heat exchangers do become clogged..   wheather an exhaust exchanger or a coolant exchanger, most now adays have coils that are made of stainless steel, no wear problems..most will last for life...unless they get frozen...   I find propane heat exchanger to be the HOTTEST of HOT...but also dangerous...I personally hate working with propane.  and I'm not willing to pay the extra that it cost to insure