The newer Prochem Legend is great I have a 06 and the heat is awsome it's good for about 250-300 feet out from the truck. After 300 feet it isn't worth anything. Normally you will use 50 to 150 on a residental job so, this is ideal.
I owned a 96 Prochem Leagend and it did not heat up very fast and I was lil disappointed. The older Legends only had 1 heat exchanger and the new one has 3.
My preference is the Butler System. This the best system in the business (MY opinion). You can go out 500 feet no problem. I had a 06 Butler and they are the Cadilac of Truckmounts. Another thing they last a lot longer too.