As mentioned by others on the thread, the positives are :-
Less surface to surface friction between the running line and the rings.
Less weight, so faster recovery and less line slap in the initial stages of the cast, ultimately resulting in less friction.
Do less rings soften the blank? The only reason that I can see that a blank gets stiffened by a rod ring is the bracing effect that the ring and its whipping (or tape) gives over a small length of the blank. How significant is the stiffening? I would set the rod up with the butt on the kitchen table, weighted down to hold it in place, tie some line around the butt an then thread it through the rings and tie a weight to it and measure the rods deflection. Do this for the same rod using the same weight with 8 rings plus tip and 6 (or less) rings plus tip, and see if the deflection is different.
If there is a softening effect by less rings then you have to see if the softer rod setup which gives a shorter effective length but less friction during the cast is better than the stiffer rod set up which gives a longer effective length but greater friction. The bottom line here is there is no easy answer, and at this point I would say suck it and see (try it out).
Also, if there is a softening effect, could some local stiffness by added back to the blank in some way. For example by tapping on some thin strips of carbon fibre at various locations along the blank. This would add minimum weight to the blank, but could stiffen things back up to its previous level (or more).
Ultimately for a particular rod and reel setup, the majority of distance is down to good technique with fine tuning of the equipment only improving thing marginally. But sometimes as we see on the tournament field, the differences in casting distance between competitors is so close that a 1% improvement in distance due to optimum equipment setup will mean two or three places on the results for that day.
