I invest into syndications as the LP with my SDIRA vs keeping the money in the stock market. 

I think it's similar to dollar cost averaging in the stock market.

I don't mean literally one property or one stock. 

Find me an investment like that in the stock market, and I'm all in.Good luck!

Another person with a few million in investments (mostly liquid types like stocks, no mortgages, one paid off rental property and doesn't want to buy anymore property) is make quarterly payments to the IRS. 

It appears that market folks (bond, stock, real estate, really all market participants) just keep receiving spooky inflationary signals, which are in turn propping up bond yields and mortgage interest rates.

You can negotiate a good deal right now, you can't negotiate stock price 

So now, i am considering selling it and paying off the majority of my first rental (I owe about $255k so i could payoff a big chunk and pay off the rest with added payments over a year or two), or put the money into stocks and grow it from there.

As much as like good investments and diversification from only stock, bond investing I know I would be happier without this property.  

I do not plan on discontinuing my monthly contributions to my investments in the stock market, nor want to pull any money from existing investments.