My only reservation is the idea of leaving money on the table by wholesaling instead of flipping really eats at me.

Totally unrealistic expectations and their opinion of what they are worth or bring to the table is far inflated. 

What else are MUST haves or must knows to have at the table when we are doing WHOLESALE RE?

One thing that could be helpful is to find a realistic alternative to the property and clearly tell the seller (through your agent) that you will walk away if they won't come to the negotiating table.

We closed on a deal two weeks ago-- we looked at the property the day after it hit the market and there were already two site unseen offers on the table when we got there to view the property.

It isn't easy however he has even had sellers work it so he essentially receives the rehab money at the closing table. 

Third example of why single family is so different from commercial is because you could buy a single family next week, get a thirty year loan and the only time you interact with the lender is at or before the closing table.

My question is would I be leaving money on the table considering or accepting their offer? 

Reliable sponsors will often be willing to provide a schedule or table with this information and should openly detail their past successes or shortcomings.

So if your property is in a solid neighborhood you should be fine or affected slightly as compared to French neighborhoods which will basically be put on pause for that time