I have a G9 partnered with a G7 and both are attached by their own Ergotron mounts which makes it simple to position. As my PC is using only an i7 with 1070 combo it would struggle in gaming with this so cant give much feedback on that aspect at the moment.
Yes, it's possible to have triple screens with this combination but eventually, my own intention is try gaming with dual G7 flanking a central G9. The G7 (27") while the same panel resolution is a few mm taller in screen height to the G9 but isn't going to be a major problem for me personally. Just to point out it's not a perfect match.
Compared to people using triple 21:9 Ultrawide (as has been done in the past)
The configuration I am considering would be similar in horizontal pixel count. Yet bring the benefit of the main windscreen region uninterrupted in 1000R. With a decent quality image, reasonable HDR performance, and the inclusion of G7s give a wider FOV than triple 16:9 displays, with of course supporting up to 240Hz.
So far, I've not seen anyone with this as a screen configuration.
Triple 16:9 & 21:9 Ultrawide Options
1440 x 7680 = 11,059,200
1440 x 10320 = 14,860,800
Potential Twin G7 & G9 Options
1080 x 7680 = 8,294,400 (As Quad 1080p)
1440 x 10240 = 14,745,600
Triple 4k resolution
2160 x 11520 = 24,883,200
For my own approach, the only question is how/if the borders would be a factor for multiscreen gaming with such a combination? At the moment I found the G9 plenty for gaming but wanted additional screen real-estate for additional apps etc.
See this guys channel for various G7 & G9 triple screen videos.
Here is another guy, that has an older (prior to 1000R) 49" with dual 27" monitor combo.