So it seems the rules for helicopter minima outside CTR are basically the same across the world (with 1 statute mile roughly being 1,500 metres).
Other than that we must not confuse
actual flying conditions with
minimum permitted conditions. We fly in
actual visibility, not in "minima". Actual conditions can be said to get worse if (for example) viz drops from 2,000m to 1,500m.
you could be going from worse visibility limits to higher ones.
But what are "worse limits"? If, say, the ceiling limit in a control zone is 600ft, and then outside that control zone the limit is "clear of clouds", are we saying the limit got "worse", or are we saying the limit got "better"? That's ambiguous.
In reality, when flying from a zone with higher (= stricter) limits, into a zone with lower (= more lenient) limits, our options (degree of freedom) improve.
At the same (= unchanged)
actual conditions, the only way the pilot - on existing SFVR - should be hesitant to confirm to be within VFR limits applicable to helicopters would be if he had been using the maximum extend of the SVFR clearance down to viz 800m. Then yes, upon exiting the CTR he would have to continue under IFR, as now the min required viz is 1,500m.
But that was not necessarily the case: Inside the CTR he could have had viz 2,000m (which in Class C and D airspace still would have required him to obtain SVFR clearance). Now upon exiting that CTR, with the same viz of 2,000m, he would have been well above helicopter VFR limits.
It would be wrong to assume (for the proverbial layman) that
by definition the
actual conditions would need to have improved to legally continue from SVFR (inside a CTR) into uncontrolled airspace. What could be though is that - due to approaching marine layer and/or rising terrain - the
actual conditions (here: ceiling) got worse as he proceeded.