So just to sum up then to clarify my so called ‘Option C’...
While the ARC PRO is absolutely awesome straight out of the box - with amazing functionality in both digital and analog configurations (simply by throwing a small switch on the side of the base), a few minor compatibility issues have been observed by the early adopters. Not much of a problem... and there is a range of solutions as per this thread.
The observed issue is that old curved lane changers, some digital counters and any 2-into-1 chicaine features (if they cause primary lanes1 and 2 to become electrically connected)... result in the current production version of the ARC PRO (2017) going into SAFE mode. The simple answer is to remove these track components... and then to get on enjoying the new power base in both digital and analog modes.
The reason for the above issue appears to stem from a design trade-off which causes a reversal of the signal polarities (in digital mode) for lanes 1 and 2 with respect to each other. This is of no consequence in digital mode unless the two lanes become ‘bridged‘ i.e. electrically interconnected. There is no issue whatsover in analog mode where (of course) the cars in both lanes move in the same direction as both expected and required!
But... if you do want to keep those old (disconinued) curved changers on track (as I do) then there are three options to consider. All of these are now proven effective.
Option A: modify the track wiring inside the ARC PRO (not recommended likely to void warranty).
Option B: modify all the above track parts, for example modifying each curved lane changer as described by blagard-01 in the link shared in an earlier post on this thread.
Option C: modify two 1/4 length straights by creating a 10mm dead spot in one of the lanes then cross wire underneath.
===X=== lane 2
X marks location of the dead spot and also shows the required cross-wiring (for underneath).
using Option C in practice..
1/ for absolute full digital compatibility (I believe) with all SSD track parts past and present ... insert these modified track parts on both sides of the ARC PRO. Then enjoy digital mode!
2/ for full analog compatibility... simply replace the modified 1/4 straights with standard ones... then enjoy analog mode!