Fun times!
I've had a Roland R-88 on loan from Spyder9's for the past couple months, and finally employed all 8 channels this past Saturday recording Ween at the Fillmore in Miami Beach. It's a quite nice recorder, although almost comically large in comparison to the more contemporary compact Zoom F8.
I used the extra two channels to record a second rear-facing channel and a fig-8 Side channel coincident with the front-facing center. I've been wanting to record a stereo pair of rear-facing channels for a long time, and the 8 inputs of the R-88 make doing that easy without needing to use the V3 to get more than 6 channels into the DR-680. It also makes it possible to play back a stereo mix of all 8 channels directly from the recorder, including Mid/Side matrixing of the center pair.
If I move to recording 8 channels regularly, I think this arrangement is most likely to end up as my standard 8 ch OMT setup. The other 8 ch option I'd like to try is placing front/back-facing figure-8's coincident with the wide-spaced omnis, allowing me to dial in front/back facing wide pairs of any pattern, but I can't currently support the weight of the 8's and their cables at the ends of the telescopic antennas.
Total channel count was as follows:
ch 1/2 = 4061 omnis in APE spheres (widely spaced, facing the rear corners of room)
ch 3 = 4098 supercard- 0º forward-facing center (Mid); ch 4 = Naiant X-8S fig-8- 90º sideway-facing (Side)
ch 5/6 = 4098 supercard Left/Right forward-facing pair- angled ~ +/-35º towards outside edge of stage/PA (forming near-spaced L/C/R triplet with center mic)
ch 7/8 = 4098 supercard Left/Right rear facing pair (angled/spaced such that their null angles more or less face directly forward, and such that the 5 supercard array has appropriate angle/spacing relationships all the way around.
A couple photos-
The 5 microphones in the center are the DPA 4098 supercards. The center is in the big Shure windscreen along with a Naiant X-8S fig-8 forming the Mid/Side pair. Zac, the other taper from California, was running Octava cardioids>FRLE2 and doing the entire tour.