Well, that setup in the link you posted was for a very different situation- a small-format jazz trio playing in a small room rather than a choir in a hall. In that situation I got good proximity to the sources as well as effectively eliminating reflections off the floor by positioning the microphones directly at floor level.
For a large distributed source like a choir, the typical setup is microphones spaced across the front of the choir. The important factors determining placement will be finding a good direct to reverberant balance, getting a good representation of all singers throughout the entire the choir, achieving an appropriate blend where single voices aren't overly emphasized, and avoiding pickup of unwanted sound sources. There isn't really the goal of achieving sharp imaging in a typical stereo sense, it's more the sense of massed voices, blending together with a good spatial sense and a large enveloping presentation.
With a typical choir setup of rows of singers in tiers, a number of spaced microphones hanging above and in front the choir usually achieves all that, with the appropriate pattern for a good direct/reverberant balance determined by the room and whatever else is being recorded. You can lower the direct/reverberant ratio by moving away, moving up, changing to a less directional microphone pattern, or combinations of those things.. and do it keeping in mind how each change affects the other aspects.
For a choir I'd probably first consider using just a spaced pair. Omnis an obvious choice, the CM3's if you needed a bit less reverberant room sound, or a spaced pair of cardioids if you needed even less. A spaced pair, or three or four, achieves a somewhat a more similar path length to the singers who are farthest away rather than highlighting those closest to a near-spaced pair in the center.
It's when there are other sound sources or instruments in addition to the choir that you need to add other microphones or pairs, or adapt the setup which is focused on recording the choir to pickup everything appropriately.
The 6' spaced omnis plus center cardioid(s) setup is a main mic setup which sort of uses the center card sort of for direct-sound center focus, with the omnis providing a big, enveloping sense of space and ambience. The center card may highlight singers in the center if the setup is close to the choir, which might be good or bad. For something like chorus plus piano, if the array can be placed appropriately that directional center cardioid can provide some increased direct sound from the piano which you might want. I use that 6' omnis with center cardioid arrangement because it works well for most things outdoors or inside in a good sounding room when recording from somewhere around the sweet-spot of the room.
But I'd suggest going with what you know to start and branch out from that. For chorus, maybe a near-spaced pair of the CM3s plus a somewhat wider spacing of omnis (I dunno, maybe omnis something like 8'-12' apart, with the CM3 pair in the middle). That way you know you can use the CM3 pair alone and it will work. You can listen to the omni-pair alone to see what how well that works, and the wide spacing of the omnis might work very well for a choir. The combination of both pairs may be even better. Conceptually that's sort of "nearspaced CM3s as primary pair plus wide-spaced omnis as secondary support."
If find you need more direct sound without sacrificing too much of the big openness of the spaced omnis, you can try the single center facing cardioid between the 4' to 6' spaced omnis. That's more of a dedicated array, as you would't use the center cardioid alone in isolation without the omnis. Conceptually its sort of "spaced omnis as primary pair plus center cardioid as secondary support."
Since we were talking about low-frequency balance previously- Microphone height also effects the bottom end response. Farther from a surface the bottom end becomes less reinforced via boundary effect. That's easily heard at amplified concerts where sitting on the ground is super boomy even compared to standing (ignoring the muffle effect of bodies blocking midrange and treble), and mics raised high are still less effected by and over-emphasized low end.
