Could you be so kind as to answer the following about about your kits:
1  Is the main difference between the GMC-200 and GMC-300E the graphics display and real time clock? 
>>Those features are worth the price difference by themselves, but add on the other benefits:  Data logging on the GMC-300E while power is off to the PI and GMC-300E.  The GMC-300E is power by the USB connection from the PI, so only one Power supply needed and included.
2  Are both units safe for mounting outside in the elements?   If not, is there a recommended enclosure that will have minimum attenuation of the radiation readings yet protect the unit?
>>NO neither one of the units are waterproof,  I have three units outside, one on a porch, one in a birdhouse and one in a greenhouse.  All three running great for over 6 months.
3  If the internet goes down can I access the data of the unit onto my computer screen?   (any screen shots available as to what this might look like?)
>>Yes, it is on your local network and just type the IP address into the web browser and the local screen will come up with a three hour graph. Here is the user manual. 
https://www.netc.com/bb/viewtopic.php?f=13&t=360I noticed yesterday at least 3  RAD-CON 5  Alerts on the map on the west coast.  Any comment on that?
>>We have been watching Japan radiation stations lite up like a Christmas tree, and if it follows the jet stream, it would cause the same problem here in the US in about 3 days later.  Just a prediction.
Thank you for time to answer these questions.
Kind regards
Have a nice holidays 
Harlan@netc.com