I have this one
but it is mesh on just one side. I think it is safe though and it has been a lifesaver.
We have the arms reach mini cosleeper too, it's awesome. The mini is plenty big for what we need and fits better in our space. The third side of the cosleeper can be raised so that it works as a normal bassinet if you need to use it somewhere other than right next to your bed. The "mattress" is also much higher quality than a PnP.
PP, are you sure it's safe to sidecar a normal crib? Our cribs both convert to toddler beds too (where you can remove one side), but it needs the toddler rail on it to actually be secure. I dunno, I'd personally spend the money on the arms reach if you like the side car set up.
ETA - Here's the link to the natural color of the Arms Reach. I'm not sure why the one the PP posted looks so plush. It's mesh sides and very well ventilated. My mom lost a baby to SIDS so I'm over paranoid about things like that, and I think the cosleeper is 100% safe.