Probably very little reason to upgrade (I have two 290s). If you were using an OAG, there would be more merit in it. And also if you were using a longer f/l scope.
If neither are these options are in your current or future setup, then you'll be fine with the 120.
And when you do upgrade, ZWO have also updated the 290 recently. It's been replaced by 220MM
https://astronomy-imaging-camera.com...20mm-mini-mono