This coin...
None of the reported network hashrates are correct (suprnova, mph, chainz), I can't make heads or tails of the difficulty trying to calculate how long would it take to find a block with my hashrate and at times the wallet syncs slower than the speed of new blocks being found.
This...
250MHs reported by ccminer, not a single share accepted for hours. What is up with the numbers here, nothing is right

250 Kh/s or 250 Mh/s with multiple rigs?
The default port for suprnova (1596/1569) has a difficulty of 32 which is huge, even for a 6 card rig (1.3 Mh/s per 1070). I'd argue that's way too high even for 10 minute blocktimes but Zcoin periodically have much faster blocks (closer to 1 minute). Blocks being found faster than you can send shares is wasted hash.
And if you use the lower difficulty port 1598 (difficulty 1) vardiff will soon kick the difficulty way up then way down which repeats over and over again.
Just did a test with 7.54 Mh/s and from diff 1 vardiff jumped to 7.5 > 20.83 > 5.68 > 1.16 > 2.27 > 16.28 > 8.88 > 2.22 > 1.28 > 8.64 in 10 minutes or 70 shares. That's way too much fluctuation.
As a completely different note, my wallet is still only at 13545 blocks after a bit over 3 days.