I've been using the ASI294mm for a month now and have been very happy with the results.
I can't compare it to other mono cameras as until now I have only used OSC. It has more amp glow than other OSC cameras I've used, but i find nothing that doesnt calibrate out with simple flats. darks and bias - some people say you need to use flat darks instead of bias with this camera but I have tried both and no discernible difference so will stick with bias.
Ha and SII flats look wierd but work.
I've used it exclusively in narrowband (3.5nm) and no issues at least when using it in 2x2 bin mode and using exposures long enough to really swamp any pattern/read noise... 300s seems to do the trick. I think there's a lot of fiddliness than can add to variable experience and reports... i had a day scratching my head with some rubbish stacks when I realised that my flats (from NINA) had defaulted to 1x1 bin...that's something to watch for. Anyway proof is in the pudding ...here's a few from the last month.
https://astrob.in/5pkch9/B/
https://astrob.in/5te3pk/0/
https://astrob.in/t0wg2k/0/
https://astrob.in/qzgch0/0/