One thing I learned in this decade is there is more variance in worship bands and muscians than most others. So it can be difficult in giving experience as advice.
For my church, the pastor believes the message in the lyrics is what's important, and the musicians are there to fill background (and help diguise some missed notes by the choir). So a Rumble 100 is fine in my case, and I even use a 50-watt amp most of the time with either a single or pair 12" cab.
Weak 40-watts can be an issue for the main adult choir, but not with the children's choir. Weak 40-watt for me is my Ampeg ba-110. That thing is weak with the sealed cab. I feel it needs to be around 60-watts to be competitive to other 40-watt 10" combos.
The key for me is not so much the wattage, but the speaker. I would need a dual 10" to make it work, but a 12" or higher is fine at my church.
That Ampeg is great for practice at the church, and the Rumble 40 would be better, imo. We're only needing to hear ourselves, and small form-factor and weight is nice. I don't leave my gear there, btw. Nobody leaves personal gear there. The church has three amps but designed for acoustic guitars. Two are Acoustics, and one is a Genz-Benz. I am afraid of exceeding max excursions of the speaker once too many times.
The drummer only shows up at the late mass on Sundays. And he knows to hit lightly... amazing!
ETA: no PA support for bass, piano, violin (when she's available), electric guitar, or drummer. Electric guitar uses a small Fender champ or similar. Only the singers, and one or two acoustic players (who's volume is reduced compared to the singers on the mixer). Small mixer, and no available channels left either.