Considering this, dont forget that we ASKED for the limit after ENY sstarted.... because when numbers are low, the RATIO of players can swing widely with just a few people logging.
When ENY first went in, the late night EST crew could see almost unplayable ENYs of 40+ with as few as 15 player differentials.
An alternative:
Maybe rather than a cutoff, HTC could blunt the curve's steepness as the number of players decreases? For example, if the current formula calls for an ENY of 25 with 500 online, the penalty could be cut to 12 when there're under 200 and 8 when under 100.
Since a 50% numbers advantage hurts more with 500 online than with 50, it makes sense that the ENY penalty could be less...
Just a thought.