I'm gonna side myself with the "be cautious out there" bunch. As has been said, yes, two aircraft passing with 5 miles from each other is (most) of times ok (wake, formations, etc aside). But on a radar display, a DISPLAY of 5NM doesn't necessarily mean that aircraft are 5NM apart. There needs to be, for a reduction of minimum separation to be effected safely, some of the next points to be considered:
-system validation (when a controllers sees 5:what can it be in real life?)
-staff training (controllers, they need to know what it is they see and what it means in real life; what to expect from now on i.e. reaction times to TCAS and revise procedures)
-staff training (including technicians and engineers: what parts of the system are esential and what/when to tell ops staff?)
-safety cases (can it actually be done?)
-tech upgrades (hardware good enough, soft good enough?)
And probably more. As far as I know (secondhand) this decisions have just been POLITICAL NOT TECHNICAL. So no valid safety case, definitely no training (controllers almost get no TRG in Spain last 15 months, and I don't know about some of the support staff nowadays but do know some techies and TRG is a word they don't know too well either) and so far the system is the same. It just happens it has magically upgraded.
[irony mode ON] It has nothing to do with management trying to reduce the number of separation infringements by reducing sep. minima [irony OFF]
So for those who see this as being alright. It's still a SEAT, they just put a Merc badge on it. But it ain't a Merc, it takes more to change it than wishful thinking. Get it?