In general, government will set the assessed value lower than market value at reassessment in order to neutralize appeals.

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? 

Something light and neutral. 

You're learning about the eviction process, tenant screening (never "word of mouth" again), the power of a lease WHEN not IF a neutral third party needs to be involved, tenant/landlord laws, and managing tenants who don't care about your business the way you do. 

I assume you got a better interest rate, and I know you are saving a boatload of interest. 3) imagine year 11-30 where you are cash flowing thousands with paid off properties instead of hundreds because of these lean 10 years. 4) hopefully you can raise rents at least $100 each every year and in 2 years your cash flow neutral even with preferred short term mortgage. 

It's in great school districts, so I just listed those in the ad in a neutral, factual manner, which I believe won't violate fair housing laws as long as I avoid implying a preference. 

The property feels more feminine so you can consider a refresh to neutralize this.

This will put me at cash flow neutral and I'll let appreciation and long term rent appreciation do it's work.

I suggest a neutral tone when you send your letter and hope for the best.

Best regards, This approach is neutral and objective, focusing strictly on the criteria, and avoids discussing any specifics about the applicant’s personal situation.