Yeah, if you were communicating with a vendor rather than a manufacturer, it is likely they had no idea.
I have a Mecpow 10W that I bought from Amazon, came with air assist and cost $299. It cuts 1/8" quite well and very cleanly. If you are set on a 20W, Mecpow is coming out with a 22W soon and even a 33W. I also have a K40, but I don’t use it anymore, Diode is easier and less support items needed IE water cooling etc.
Also, Mecpow offers a rail extension kit to make the cutting area 15.7" X 29.5", it is also available on Amazon, as well as an appropriate sized honeycomb cutting bed. I purchased them both, but haven’t put them into use yet.
There is a reason, actually several, that the Mecpow X3 Pro is lower cost than the Sculpfun S30 Pro. If you are strictly after a hobby laser, The Mecpow is a good start.
What concerns me is that their module image implies there is a single 10w diode. The maximum diode power is 5.5w, and it takes good engineering and manufacturing to make two of them work together. I find it interesting that their image shows only a 60% increase over the 5w unit. Caveat emptor.
Well, I am very new to all of this, I already had a 5w Wainlux and wanted something a bit more powerful. When I saw the Mecpow, and at a great pricepoint, I thought why not. I am not sure about the engineering, But I know it works well for me. And I am just a hobbyist at this point, I have sold a few things, but mostly just tinker. I now have 5 lasers, 2 K40 Chinese lasers, the Wainlux, the Mecpow 10w & a Ortur 5.5w with the rotary. The K40 works great, but it is much more cumbersome to operate, so I mostly just use the Diode lasers.
Impressive! I had two lasers until I converted my 3040 Pro back to a CNC Mill. I looked at the MOPA fiber machines today, but realized I would have to work to justify the purchase. That would spoil retirement, so I got over it. 
i have been really happy with the neje branded machine
specifically i use it with a (nominally) 5.5 watt N40630, to cut balsa and light ply, which it does easily although not on a single pass except for quite fine wood
more info here : https://www.rcgroups.com/forums/showthread.php?4038567-neje-master-2s-laser&perpage=30#post48396303
if you intend to only cut balsa up to 5mm (as long as it is contest grade, not the heavy stuff), or light ply, it is perfect
if you are using pawlonia, you may need more power (or really, more passes) to get the cleanest results
as for a hood, the top of my induction cooktop with extraction fan for cooking, and an air assist is more than adequate for the smoke it invariably generates
It is good that “we” can also be realistic once in a while, although we are a little older. 