Cost Segregation -- What is the true benefit of the accelerated depreciation?

[Bob Dole]

All,
Apologies for the newb question, but I just heard about cost segregation and have been reading up about it online.

My understanding is this (and please correct me where I'm wrong):
Pros:
-accelerate depreciation, front load (vs. just a straight line over 39 years)
-save money on taxes because of the depreciation

Cons:
-if I sell the property, the recapture will be larger
-not recommended if you flip properties

So hypothetical situation:
-Majority of our income is W2 based, let's say it's $500k
-Net income from commercial rental is $100k
-Income from dividends and interests is $100k
-Both of us are full time W2, so non-prof real estate (but this can change  -- please see below)

So we're hypothetically grossing $700k a year.  If we do cost segregation how much would we reduce our taxes by?

-Purchased a commercial property this year for ~$2m.  The estimate I have from a cost segregation firm is $316k (w/ study) vs $28k (no study)
-Assume we're in the 37% bracket
  -Does this mean, I can claim a $117k depreciation deduction for this year?  Essentially lower my taxable income by $117k?!  So instead of a $700k income, we'd be looking at $583K instead?  

As I mentioned above, we're both W2 employee.  But one of us no longer is a w2 employee as of Oct 1.  Can this person now be "a real estate" professional?  What's the advantage here?  BTW, the rental property is cash flow positive.