I’ve got the 2.8 and love it. I recommend the ebay lens. It works very well with the 2.8. Pro tip from those that came before me. Get a piece of black anodized aluminum and use that to focus your laser. I use a spare AR15 lower. 
You can do glass if you spray paint it first. There is a thread around here on it somewhere.(Found It)
Clear acrylic etching doesn’t work great with the 2.8 with any method. Its not that it doesn’t work but it takes so long you will quickly wonder why you arent using a bit. I have had mine since 2015. It went on the x carve before the spindle. I have had a lot of fantastic help along the way and am willing to answer any questions and share any comments, suggestions, tips that are JTech 2.8w related. Gotta give back and pay it forward for all the great help I received
Quick shout outs to a few of those that helped me
@picengravertoo
@JohnChamplain
@JTechPhotonics
@RyanCook (For the info on glass etching)
@IanWatkins (For the write up on electro etching)