Anthem - when you have a minute could you create a little matrix along side those prices with the advantage of each? And add the DDA GPS to it as well.
Things are in flux with the more entry level stuff but here is a quick break down -
DDA+ from Ducati (600, or included with Tri/R) - full access to ECU data (rpm, speed, temps, etc). If you add brake pressure and suspension pots, add 4k to the equation although realistically you're more interested in half of the setup (front brake, front suspension). If you do get the 4k SSTK package, that data will also be available to the other units listed below that tap the ECU. Data is displayed on stock dash, but limited to what you can show and display. Software from Ducati is "average".
Starlane - athlon (they also have stealth(lower) and Davinci(dash) Athlon price is around $800 I believe - about to have full access to ECU so it can log data. Excellent GPS lap timer, shift lights, etc. Before the ecu connection, you had to wire in K rpm line, and other sensors. Now tapping the ECU makes it simpler. Will have same access as DDA does - and has the ability to add a few extra sensors. Semi-portable in that you can wire two simple harnesses into your bike (power,rpm, etc) and move the display to bike to bike to bike. Digirace software is getting better and probably already better than Ducati/Prosa.
Aim - start getting into some serious Data acq at this level. Excellent support in the US (east and west coast). Taps into majority of ECU's for bikes, cars and karts. Can expand analog and digital inputs, multiple display options from a simple lap timer, to configurable lap timers, to complex dash units that completely replace oem dash. Evo unit has tri-axial accelerometers and GPS built in. Also has logger dash units that display and log at the same time. Integrates with their smartycam camera system that is heads and shoulders above everything else out there. HD version coming out in a month or two as well. The smartycam - allows you to overlay whatever data the evo is getting from ECU and overlay that onto the video - so you can show rpm, speed, brake pressure (if you have the sensor), suspension pots (sensor), temps, etc, etc on the actual track video. Then you can see as you're riding the track - where you braked and how hard on the actual video - when you got on the rpm, how hard, how fast, how long, etc. Everything into the RaceStudio 2 software suite - very good software and significant improvement over previous mentioned.
Motec, Pi/Cosworth, MM - all grouped together as these are the race team stuff. You are looking at 5 figures to the sky for most of these. They generally replace the ECU and give you a nice bundle wire harness and you're responble for wiring the bike together AND programming the ECU. Sounds difficult, but most bike/ecu programmers can do the basic stuff in their sleep. It's that final 2% that makes the difference between winning and rest of the field that takes the real genius. They have video recorders that sync and just about anything else you want - but it isn't very end user friendly. The size of the boxes are also a challenge. .. Software is generally free (or very low cost) because they know its useless without their hardware. i2 from Motec is top notch.
Thats about it in a nutshell. As DimST mentioned, Starlane is creeping into the bigger fish territory. If you aren't doing consolidated video - then that platform is a serious contender as it has easy ECU connection data now and very motorcycle functional mini-dash/lap timers. If you want video sync that is easier than using a 3rd party software(eg race render, trackvision, etc) to match the exported starlane (or other) gps data with some track video (like hero, contour, etc) - then the aim stuff with their smartycam wins hands down. Not cheap though as smartycam by itself is 1k
Here is an example of data into aim data loggers synced to their smartycam camera. You can customize the controls you want to put on their, the logos, the dials, whatever. But it takes the data from the logger and overlays it onto the video automatically at recording.
http://www.youtube.com/watch?v=oFfaXKkWQI4&list=UUi9nUjNotkdKzZQr3gca3Gw&index=29
You won't believe how much you'll learn about your track riding with one session with just that data/inputs overlaid on top of your video and studying that. The hardcore data acq for the rest is half how to make you better and also how to make the bike better but is a lot more work. This type of video is instantaneous to address the first 90% - the last 10% takes a lot more work. But 98% of us need to work on the 90% and not the 10%.
Ok, whew - enough typing.