My two big EG4's have pushed out just under 12MW since June. I've had a few hiccups here and there, some related to the inverter, some to batteries, some to interaction between, generally around edge case events. I'm expecting the latest firmware update that should be out soon should resolve the bulk of any lingering significant issues, and hopefully not introduce any new ones. The Sol-Ark is a much more mature product, and the firmware appears to be somewhat more robust at this time. If maximum stability is paramount, it's probably a better choice, though probably not so much in a year or so. i.e. If you are designing for 6 months out, I'm not sure it's going to matter that much, and it also depends on how complex your needs.
A lot of the guys here have been at this for a long time, and like to play with their toys, so they have DIY custom batteries, and a bunch of MPPT/SCC's, and stand-alone inverters, and they've wired it all up. This can make for a very flexible system, but I stopped building custom component stereo's and computers a while back, and frankly, the advent of relatively inexpensive AIO's, that simplify installation and reduce component count, is what attracted me to finally take the plunge in the first place. I looked at Schneider, and Midnight, and a few other systems before I put my crap together, and every time I looked I ended up with something less capable, and/or drastically more expensive, as well as more complex. If you started 3-5 years ago I think it would be different, but I think building out a component based setup with the AIO options available today would be silly. YMMV.