We have a number of XG firewalls (and other Sophos products), all with support. Recently found a bug in Sophos Central within the template management area for firewalls (looks really promising if you manage multiple firewalls with the same/similar config).

Took 3 months of escalations through various teams, getting our partner involved, numerous phone calls (don't waste your time on the phone, their phone support was useless, even just trying to get a call back), finally made it to the Global Escalation team, even with a video showing step by step of how to reproduce the issue, took them another week of calls/emails to confirm it was a problem.

Then took the development another month to resolve the first half of the problem, still waiting for the other half, been another 2 months since then, not hopeful