I finally got the mic to use with the RTA portion of the DBX DR260 and just did a quick analysis of a 4628B Cabaret series centered at 1 meter, but didn't move it outside - I just had it sitting on a carpeted floor in a fairly absorbant room. It was too windy to do it outside pointing up today - I'll try that some other time and check the difference.
Anyway, here's the curve I got, (interpolating the ISO frequencies with the graph I had). The DBX mic has about a 1db curve up at 10K, then back to 0, or the high frequency might have come out a little flatter. The DBX RTA also starts at 25hz and ends at 16Khz, (I didn't graph 25hz - it just keeps falling). HF adjustment on the 4628B was at 0. With a little judicious EQ these sound pretty good, especially for what they are.