I haven't been hanging around on the forums much lately, so I might not be totally up to date on the latest technology, but I've never heard of a total conversion to propane. My truck has propane injection but still uses diesel as the primary fuel. The propane only kicks in when the boost reaches the preset level and adds power by improving the operating efficiency of the diesel.
The result is a true 80rwhp measured on a dyno. Regardless of what the chip/tuner manufacturers say, that's a whole lot more than any chip/tuner can do on a truck like mine. I know, I've tried them all.
There is the additional expense of needing to fill the propane tank, so it isn't truly a cost saving move. Some report that they see a noticeable gain in fuel mileage as a result of adding the propane system, but that isn't what I bought mine for, and suspect that the additional cost of propane offsets the gain in diesel fuel mileage.