I think you are on the right track.
You might search for Mardi Gras recordings on archive.org and look at the equipment used there. It's not so easy thinking of where you could find something exactly like what you want to record. Moreover, I doubt that the people you want to record line up in a choral formation to make things predictable and easy for you. That makes me think you would want to be in the middle of the event and use omnis. I haven't experienced what you have experienced so I may be badly wrong, but if the sounds you want to record are coming from all around you, looks like omnis would be the best choice.
Have participated and recorded many drum circles/percussion/instrument outdoor sessions and think it is a hard event to record.
As "2manyrocks" states each drum circle/percussion/instrument event is different. Sometimes we line up straight with 2 groups facing each other. More like lines of people. Then other times we have small circles maybe 15 feet wide up to large circle up to 60 feet wide. Then other times it is people just jamming in a straight line and could be up to 60 feet difference between first person inline and last. Sometimes the circle/lines move during the event. Could not list all the different configuration that are possible here.
What I have learned is:
Where you place the mics are critical.
What kind of mic you pick to use is important.
Every session is different - You might need to make changes on the fly.
Outdoor conditions make it harder...wind, rain, heat and the difficulties this cause with the recording and gear.
What I have found, In a circle you can use omnis and it picks up the group relatively well...whoever is closet to the recorder/mics is usually loudest though the bigger sounding instruments can overpower the other instruments. There are problems here with many instruments are at different volumes in the recording. If it is a line of drummers or performers one set of omni mics is not going to pick up the performers at the ends very well. Tricky to get the levels set on the recorder properly due to performers coming/going and changing position in the circle/line all the time. Usually I get a pretty raw recording meaning there are problems with the recording each time due to some issues listed above and others. Some recordings are hard to listen to and do not sound good.
When the people speak in a drum circle it is almost inaudible in the recording due to the levels you set your recorder at are set for very loud music. Sometimes we play at actually outdoor venues and I can set my cards/omni mics up in back and then the recordings are more even and balanced. Though these recording sound distant compared to having an omni's in the center of the circle.
Also found some drummers/performers do not like you to record them. This can be a tricky situations due to so many people in the group and if no rule about taping has been established. Been told before these sessions are not to be recorded in very stern voices.
If I was going to go for a one device solution I would get the best recorder with omni mics. Not sure how much wifi helps you here in reality. If you have to move the mics...battery life...distance you can pick up the wifi...can not monitor recording on device...etc.