whats up with your firmware? i don't think you would need to wait for solidoodle to release something to be able to adjust your extruder steps per mm in Eprom. in RH its config>firmware eprom configuration. then once in there, on the first row, you'll see the first line with x,y,z,e with boxes + numbers beside them, these are your motor step per MM settings. simply change the number beside E to what ever your calculated number is. i think default is 130, mine is somewhere in the range of 102.45 after the 100mm calibration test.
after setting the E step to what you calculated it should be, mark another section of 100mm of filament and extrude 100mm to test, if your within a mm or 2, thats good enough. if your a little higher, try lowering the steps per mm by .05, a little low, add .05, etc. just don't use large numbers to make adjustments once you get close with the calibration steps. remember that this is steps per 1 mm, any change here will be magnified 25000x when your printing something using 25000mm of filament. lol
after getting that sorted to your satisfaction, set your flow multiplier to 1 (yes, 1). and print a test cube with 1 perimeter and no infill, i think there are some test cubes on thingiverse that are only 1 wall thick and top/bottomless so you can print with normal settings. use your calipers to measure the wall thickness. can use the same calculations as for extruder step/mm to determine the ratio, wall thickness should be .42 mm be default. with a 1 as your multiplier it will probably be .55 or more. by setting the multiplier to 1, its very simple math, simply divide what you should have by what you got. in this case: .42/.55 = .7636. set the multiplier to .764 and try another print, measure the wall, should be pretty close this time. can do the math again, or simply add/subtract+test.