I have the same problem as Mathieu, one brand new big MGE UPS that can communicate with all the equipment in the rack but the XSR Enterprise. And I agree point by point with all Mathieu said. When you buy a "enterprise" product you think on the 'full' thing (This is what I was thinking when I recommended it for my company). I rely on MGE because their basic communication systems works great and easy on PC's, MAC's and so on and it's very reliable, I tried APC some time ago and I find it less reliable.
I beg you to think about implementing the 'server' or the 'client' mode for MGE in your product.
Maybe R-3 is better and so on, it's OK because it's a new product and must be better that the old one, but why abandon XSR Enterprise? It was your flagship only some months ago... I bought it 6 months ago and now you are saying that, maybe, you will never implement the support for MGE ups slave or master mode... It's frustrating...
I realize the frustration level, but currently the main developments are in R-3 and as for the NAS XSR Enterprise I have no time table as if there will updates to fix this currently. The reason for R-3 is because it is based on our DSS engine - meaning one update will be for all R-3 updates including SOHO, SMB and iSCSI R-3 family. Instead for each independent update for all products of the XSR family.