SEP IRA is the incorrect type of account for you. Go with a Solo 401K. Not sure what is involved in switching, but you can defer way more with a soloK than a SEP at your income.
As a bonus, anything you defer into the SEP / soloK gets deducted from your MAGI, and you're at an area where you could pick up some tIRA deduction space as well.
ETA: And actually, that extra tIRA money should factor into your S-Corp salary vs. dividend calculation, if you'd use it. Might even get into the saver's credit range, which would further push you towards taking salary.
Not sure of your exact numbers, but it is conceivable that the S-Corp is actually costing you more on saved income tax than it is saving you in self employment taxes. If you are able and willing to max out a SoloK and a tIRA. This is where doing your taxes yourself can be a huge boon - probably 90%+ of your accountant's clients are better off taking a lower salary from the S-Corp and therefore paying a higher dividend, but if you want to save a ton as most of us do on this board, you might be in that 10% that is an exception to the rule.