In the case of the safety line moving through choke points, one consideration might be the LENGTH of line which must pass through the choke point because the longer said length is, the more opportunity exists for a problem to develop.
The longer the line either redline mini 5th or single line flagging, the safer it is. for a single line flagging system you need wingtip distance to safely flag a kite. If you set the distance shorter than normal, say 8 meters instead of the more normal 10 meters, on a light wind kite you can cause a flag out failure because the distance is too short. On a redline mini 5th system like a 2013 cabrinha or best, if the redline is too short for a kite it might have a bit of tension on the rear lines and never flip into the "U" position and completely depower. The over riding consideration here is the safety of the control bar, and this means the longer length of line is going to be safer that's just how the control bars work.
Shorter length of line thru the control system is one indication that the bar might not be safe with all types of kites.
I thought you had in mind a specific control bar, I am familiar with most of the control bars out there, which is why I didn't understand your criticism of the small holes the safety system lines have to pass through -- except for 5 line bars they all have this particular limitation.
Most of the older control bars were awful they learned a lot in the last ten years about safety. But nearly all of the modern bars especially 2013 are very good.
Larry if you don't like the way the cabrinha bar works you can always use your old bar if you want, it should be fine to use a single center line flagging bar on a cabrinha kite.
Will the single line flagging 2014 Cab bar work on all years of the Cab IDS kites?