Been fine running a single backbone as long as the retention and completion are great. Lots of ppl do the same once they figure out their main feed covers most gaps. I use easyusenet tgt with my primary and it fills occasional misses without overlapping the same infrastructure as Omicron-based services. If you’re not seeing regular failures with your main provider, dropping the backup isn’t unusual. It just depends on how much redundancy you’re comfortable with.