It really depends on when you are using it. In between runs on the small screen of the device I don't get as in-depth as when I get home. At the event I'll have the runs chase each other to try to examine different sections and I'll look at MPH through sections. I only use the Full map, I can't wrap my head around the zoomed map at all honestly. At big events I'll try to walk the course with my datalogger in my hat or something and get a base run. Then I'll set beacons for section times and then it's easy to compare section times. You could also do this based on your first run. I usually end up not setting beacons until we get home, especially at local events.
Having datalogging between runs can change how you approach things. Andy Hollis (from Texas) is very good at this, from what I've seen. You have 2 sections you aren't 100% sure what the best way to attack it is. So you run it one way your first run and another your 2nd run. Then you compare and do your 3rd run the best way on both sections. Whereas I usually make some sort of plan and stick to it, I've found myself experimenting a little more (and I should do even more) and I think it helps.
A lot of times you know whether it was better or worse, but you really don't know by how much (even if you think you do). I've found many times that a section I though was a LOT better was only worth a tenth and a section I thought was a little better was worth 1/2 a second.
It's also useful for figuring how much time you left out there if you don't feel like you ever had a great run. On Monday, I knew I had a couple runs where I ran the front side well, but the backside sucked and a couple runs that were the opposite. Using the data I was able to determine that I could have gained at least a second if I had put a run together that was good on both sides. Beware, sometimes it results in wanting to kick your own ass [;)]
I've looked at data on the DL1 and it is definitely better since it has actual accelerometers. But it's a lot more expensive and the ability to look at the data during the event is reduced. If I was road racing or even doing lots of autocross test and tunes, I'd go with it for sure. But for autocross I chose the MaxQ.