EDIT: After running the 256 for about and hour or so...I have noticed two things. 1)I get quite a bit of work restarts. 2)I get quite a bit of detected new block. This appears to lead me to my concern....cgminer is reporting what appears to be a lot less accepted work since the change. I am at about .5% reject rate on 1.8MH/s. Is this normal, or is there currently an issue on your side? ...OK just looked again and now ive got like 10 straight accepts...it seems to come and go in spirts. Is this normal? Thx.
Work restarts and new blocks have _nothing_ to do with your worker diff. That's just because we are mining a fast coin, or switching between coins quickly. Periodic rejects are normal (it happens when 2 blocks are found within seconds of each other, or a new block is found and then we switch coins right away). Under 1% reject rate is great.
I am mining one rig with an average hashrate of 1.785 mh/s. I am having a reject rate of 1.88%. Is this abnormal?
Also yesterday I logged in and have found 21 blocks and today it went to zero found, is this an error on the site or is my machine having a problem?
That is a fine reject rate. You could probably tune your rig a bit for a slightly lower rejects (set expiry to say 5, and queue to 0, and maybe lower xintensity slightly or use 2 threads if possible), but for say a 1% gain in accepted shares, it's not likely to be worth your time.