Had some time to play with the Sprog/JMRI combo tonight. First impressions:
Installation and setup is a bit more time consuming than I'd like but, it's straight forward.
The interface leaves a lot to be desired - at any time, there may be 4 or 5 JMRI windows open for different things. It's a total hassle to have to find the one you actually want. This could be solved by having tabs within one big JMRI app screen.
Specifically for programming, the ESU LokSound programmer is a bit better. The ESU unit is much faster to read and write CV values from/to a decoder. The ESU also has throttle available right there so you can check your changes immediately - this is particularly helpful when playing with the motor settings.
Once the interface is set aside, the combo is huge bang for the buck. The highlight for me is the one thing that LokSound Programmer is missing - making changes to non ESU decoders. And, making them in an easy way as opposed to fumbling between LEDs and a few buttons like the Lenz Compact does. No need to enter CV addresses, or numerical values - just a simple intuitive display of what's what.
The second highlight is the throttle control. Took about 2 minutes to set up control from my iPhone with the WiThrottle app. The "lite" version is free (it's what I'm testing).
That's it until I have more time to play with it and learn all the other stuff it does.
Overall, I'll say the following:
Setup and use can be a bit annoying. But, for $100, you have a decoder programmer for virtually any decoder you're using, you have throttle control, you have switch control and, if you have a smart phone, you have a wireless throttle. Can't beat that. I'm happily keeping the Sprog

Now it's just a matter of adding a big power unit but that's the case regardless of the controller.