The Due On Sale clause was added I think in the 1980s because of "sub-to" deals.

I have the credit, experience and the knowledge on how to underwrite the deal to show their ROI in this arrangement vs a traditional sale. 

Usually in the year following your purchase, the property appraiser will reevaluate the house based on the new sales price.  

I am aware of Crexi, Bizbuysell, and Loopnet and reach out when I see something for sale on those sites.

I had the initial call with a PadSplit sales person, but I wanted to talk to somebody who's actually doing it to get their perspective and advice.

Your new ARV(after repair value) should be supported by an adequate amount of comparable sales in the area(duplex's).

Also, not very easy to use typical methods of valuation like comparable sales - there is no public tax assessor's website that you can just freely grab this from. 

Here are the specifics on our Seattle house: 5br 4ba 3,400 sq ft, built in 2019, $1.7M est sale price, $5.5K-$6K/mo est rental value, 4.0% mortgage with $3.3K monthly payment, around $1M in equity. 

Found a property which is Sheriff sale, really promising.

You didn't mention where you are operating, but depending on average home prices, I think you'll be ok.For instance if we're talkin $500k homes, and if you will get a 2.5% commission, split that 50/50 with your Broker, you will end up with $6,250 per sale, right?