Dashhawk. I think logging is a great feature. You can do a run without constantly checking your gauges to see what you are holding/ spiking, you just upload a logged run. Also usefull for pulling AFR's and comparing them offline to your rpm's.
I plan on using it at the 1/4 mile to record how well i'm driving by looking at throttle position, shift times, rpm shift points ect. It's kinda scary to watch how fast heatsoak occurs during staging.
The dashhawk is a more in depth tool imo. If you use it to its fullest. For example, I should be getting my forge bpv in the mail next week and I plan to do a few baseline runs with the stocker, looking at boost psi, rpm, speed, retard, boost temp and intake temp. I'll then swap on the BPV and do the same run. I can then overlay the graphs and see if boost is building faster/ holding higher and see if intake temp is affected in anyway (doubt it, but eh i can log 6 variables so there). This way I have real data to check and see an actual increase not just "it feels faster". I'm pretty paranoid and ocd so I hate spending money on performance without a way to quantify the results, this gives me some peice of mind....
-mk
(drunk) + (five-0) = (killit)