Recognize there are challenges doing BRRRRs since the rate increases that have occurred in the last couple years

Increase in property value as a long term hold until the right number comes around that you were looking for. or b.

I don't know if I'm getting much appreciation on a duplex unless the rents are significantly increased.

The shorter the prepayment term has an impact on increasing the rate.4.

That sounds like a lot of work and I'm sure he would prefer to avoid that work and just sell it for $1.9m or $2.0m.if I were to buy it from him, to get to cash flow neutral I would need to increase rent on all 6 units to market rates and my monthly payment would need to be close to $6.2k/month, which would be $100k down payment, $1.7m loan with seller financing at 2% interest rate and flexible ballon payment.What would you do if you were me? 

That sounds like massive renos (ie new floors, painting...).Yes as you acquire more properties, the chances of having multiple vacancies (no matter how leases are staggered) increases.

I like the cash flow and see the potential for increasing rents, but I’m hesitant about overpaying.

Pretty incredible how rapid the demand has increased in the past 12 months especially. 

How about the increased home insurance cost for a landlord policy?

This eliminates the problem of increasing your debt and damaging your credit score.