For every 10 high hp dmaxes there is only 1 duraflight
I think that is mostly due to initial cost, plus there are a lot of guys who don't know about them, but once you start adding up what it cost to rebuild the Allison, especially if you don't do the work yourself it starts looking like a good investment. Much lighter (100 lbs) shifts much quicker and doesn't freak out. Allison is a great pulling tranny and street tranny, for those guys who do both drag race and pull it is the best I believe.
Just look at the quick 50 list top 10. The top 3 are full out racing rigs. #4 Duriflite in a full framed truck 4x4, #5 Duriflite in a full framed truck 4x4, #6 4L-80 in a Mustang. #7 Allison in a light back halfed truck 4x4, #8 Allison in a 1/2 ton 2x4 truck, #9 Duriflite in a full framed 4x4 #10 Allison in a full framed 4x4 that couldn't make 3 passes without blowing up the tranny. The rest of the top 50 are for the most part Allisons, #12 and #29 are new Duriflite trucks and just getting the bugs worked out.
To each his own, but if you are interested in building a very fast high HP Duramax and want the best chance of success while keeping within the NHRDA rules of having to have a transmission that came from a production truck, have the least amount of breakage then I still believe the Duriflite is the way to go.