Your PI values are OK but not impressive. Your PIF values are very good.
The ECMA-337 standard says that the maximum value shouldn't be higher than 280, and the maximum PIF value shouldn't be higher than 4.
Total or average values are not mentioned in any official standard, but you'll se plenty of opinions and personal "standards" on this subject on the CDFreaks forum.
4x is the recommended scanning speed for the LiteOn 1693S and all earlier drives (**1S, 2s and 3S).
For the 1635S and newer drives (5S and 6S) the recommended scanning speed is 8x. For most discs the difference between 4x and 8x scans in these newer drives are not very big however.