[msendit]

I run a SOLO 2 DL, but no SmartyCam (I use a GoPro + RaceRender for overlays instead).

Pros:
- everyone around me seems to use some AiM datalogger (various solos, dedicated dashes, etc). That's really the big one and the main reason I got one too. Most of the racers / fast people have a ton of data at a lot of paces and don't mind sharing it. One of the ways I've improved the most is asking someone more experienced something like "Hey, I'm trying to break 1:XX, happen to have data around that pace?". Many times it's a very different car (read, a miata), but you can still learn a lot even from that.

- when it works, it's conveniently set-and-forget. I still have a bad CAN connection (long story), so dealing with that has caused me lots of a pain, but that one's on me. When you plug it in the OBD port, it's as easy as it gets and just works.

- the predictive timing is pretty good. Just make sure to mount it somewhere close -- the screen is a little low-contrast.

Cons:
- the software is downright terrible. Windows only, with a UI stuck in the early 90s. Not to mention, slow. Still baffles me how downloading a 2 MiB data file from the solo over WiFi takes something in the minutes.

- you can't just step out of the car and get immediate feedback. You have to fiddle with a laptop, wait ~forever for the data to download, etc. As DYoung mentioned, a trailer with a dedicated laptop might solve this. Because of this, I also run Harry's and usually only look at the Solo data at lunch or when I make it home. For a quick, "I lost a full second at T5", it's hard to beat a couple of taps on a phone after you pull into the pits.

I haven't tried the SmartyCam, mostly because: (i) it's expensive; (ii) video quality is meh (720p@30fps is pretty old by camera standards now); (iii) it overlays at the time of recording and you can't change it after (your RPM channel was dropping data today, tough luck, there's a giant tach showing 0 in your video now); (iv) it uses the same terrible AiM PC software.

GoPros aren't without issues either, but at least they are so popular that there's often workarounds for them on the internet.