My first machine was a Solsylva, and it served me well. I did eventually upgrade my system, but I did retain some of the comcepts, like the raised rail design, dual X leadscrews (run with timing belt and pulleys).
The upside is that it's easier to make a ridgid gantry when the rails are raised. The machine can also be placed over large workpieces, or even a floor. A removable tabletop could be a great way to implement a rotary axis.
The downside is loading parts over the rails. But almost all the cuts are square and it's pretty easy to substitute better parts like leadscrews and such.
The joes2006 does look nicer and has a large following. Having a CNC to cut it is a plus. The carriage assembly and bearing concepts are similar to solsylva. The downsides are the singular leadscrew on the X, and the single-ply gantry uprights. I've seen a lot of them where the gantry was reinforced after the fact.
Solsylva is made of solid wood. joes usually of MDF. I prefer wood myself, and maybe you could use some wood parts on a joes...
If you go to the gallery page on the solsylva site, my machine is the bottom most on the page, with a link to it moving... You could also check my youtube channel for more vids of my machine and the build thread here on the cnc zone.