The advantage of submitting through Mika's (or others) is that you get a true count of the blocks you did. When you send directly to DNet, some blocks won't get creditied because someone else was cracking randoms that just happen to fall in the same range as you cracked.
THuis when you check your stats on DNet, you get a number you were credited. When you check Mika's, you see the actual number you did. =)