My guy is good, but he's also too busy for his own good, and thus leaving money on the table.

More than once I have gone straight from the closing table to the bank to initiate a refi that same day.For now you're probably better off waiting out the 6 months and taking advantage of the better terms you're getting but at some point you will start buying properties using your LLC and embrace the world of commercial loans. 

is 100k enough to bring to the table for a new investor into a deal?

Keep it about the seller and the benefits do you bring to the table.

I would say not to be so naive and think they're motivated enough to leave $100,000 on the table.

I simply do not know enough to say that a 5/20 year balloon was my only reasonable option on the table.

Here's a table of the number of years, given a rate of return you need to turn $1M to $5M. 

I am not sure how or if you can convince him of 50% unless you start bringing some of the work to the table.

I haven't spoken to the husband this month, I'm wondering if this is all going under the table without his knowledge; planning on reaching out to him later today.

NO one is perfect on our side of the table.. all you have to do is follow the crowdfunders.. some of those investors are sitting on 20 to 40% of portfolios not working..