2.5W or 5.5W laser ?

Hello. Could you provide some insight about choosing a laser?

I'd like to buy a CNC3018 Pro machine off eBay primarily for light milling. I would also like to purchase a laser with it and ultimately be able to burn images such as portrait photos into wood materials.

With the machine I can choose either a 0.5W laser, or a 2.5W or 5.5W.
I am tossing up between purchasing either the 2.5W or the 5.5W.

I am leaning towards the 5.5W laser, would this be overkill for my application? I see that I can adjust the minimum and maximum power output via software. With a 5.5W, whether I have to adjust the power output or not, would I be able to achieve very light tones and "shading" to reproduce photo-type images with good results? Or would I be better off with the lesser powered 2.5W laser? Would the 2.5W produce smaller finer details than the 5.5W?

Also, I assume it would it benefit the longevity of the laser to be running 5.5W at half power rather than 2.5W at full? Is that a fair assumption?

My apologies for my basic questions. What's your opinion? Any advice or recommendation would be greatly appreciated :)

Greetings! Remember that you can control the effect of the laser with travel speed as wells as with laser power. I would go with a 5 watt as you may want to do some (quite) light material cutting down the road, or deeper engraving on harder wood or composite materials. While there are a variety of ways to control the laser, gRbl based controllers are most common, many folks really like Lightburn software. It isn't open source, but it is available for mac, windoze, and linux. Treat yourself to GOOD laser safety glasses/goggles, wishing you had after something reflects unexpectedly won't fix the damage.

OK Stan, thanks for your reply! Yes I'll make sure to get some good proper safety glasses :)

Any other thoughts or tips from anyone else?