I bought a diode laser with similar power power 3 months ago (
xTool 20W D1 Pro), and for LPR/MPR sized projects it is perfect. I get clean cuts on the 2mm and 3mm plywood I got from Amazon. Using the rotary is a learning experience, LPR tubes are not easy to hold straight, so plan to make some jigs to keep everything in place for those. I have some ideas on improvement for my rotary, but I'd like to get a better enclosure first. Larger tubes have generally been easier to cut. Engraving tubes to mark them has been difficult, etching deep enough to leave a mark usually weakens the tube.
I have no experience cutting anything thicker than 1/8" yet, but I can theoretically do 10mm in a single pass. My initial plan for thicker pieces was just to cut out 1/8" templates and route the pieces, but I've since learned a local library has a maker space with a 80W CO2 laser, so I'd probably use that instead.
If you're looking for a smaller laser, consider getting one with an open frame like the D1. When cutting longer tubes, I can remove the enclosure and allow the parts of it to extend outside of the laser's frame. You can also set the laser directly on what you want to cut/engrave, no matter how big it is. The trade off with an open frame laser it it handles ventilation poorly. I have the folding xTool enclosure and while it protects your eyes, smoke still gets out. I plan to build a solid enclosure for it eventually with better exhaust.
As far as diode vs CO2, CO2 is far more powerful, but requires more maintenance. I wanted something I could just turn on and use, and the diode laser has been fantastic in that regard. Once I finish creating my cut files in Lightburn, I go to the laser, pull up the file there, turn it on, position the material, focus, then hit cut, it takes 2 minutes. While it's largely the same with CO2 lasers, you also have to deal with focusing the mirrors and cooling the tube. I plan on moving my laser out the garage, which if you do a CO2 laser you have to worry about keeping it heated or running antifreeze in you coolant lines. The diode laser just has a little fan on it.