Just in case someone else has the same peeves... I bought an RX100 recently and while it's a fine camera, there were a few things that I really missed from my trusty old GRD: 1) grip, 2) accessory shoe (for an OVF) and 3) ability to turn off the LCD.
For 1), I got the JB Camera Designs RX100 grip-base
. I looked at the Franiec grip but preferred the look of the JB one. It attaches to the tripod socket and unfortunately doesn't provide access to the battery... but especially with in-camera charging, I can live with that. The grip is very well-made, looks & works great. (Note that it comes with both a flat screw and a larger tripod screw (the one pictured below).)
For 2), I bought some strong double-sided tape and simply attached an accessory shoe taken from elsewhere. I use my old CV 28/35 mini-finder.
For 3), I got the "Delkin Devices DU3.0-M Universal Pop-Up Shade for 3.0-Inch LCD Screens". It's about $8 on Amazon. I don't care about the shade, I just like shooting with the LCD off sometimes, and it seems like it's not possible to turn it off on the RX100. I doubt Sony will change this with new firmware, so this will have to do.
All in all, slightly bulkier, but definitely worth it to me.
(Apologies for the crappy pictures, there's a distinct lack of daylight around here)