Owning property is amazing, don't get me wrong.

Since I have done both of these things wrong and right in my past, I can tell you keeping the client happy to a certain extent is a lot more cheaperWe have found that setting the proper expectations right up front of what we will and will not do seems to help solve going down this never ending rabbit trail sometimes.

Even if you aim wrong, it still works.

I may be wrong and my CFP's may be right but I am thinking...Is it better to (1) leave the money in 401k and let it keep ballooning and invest in RE with pre-tax money? 

I bought the wrong printer first $400 down the drain.  

This is standard business practice - just look up how many settlements the SEC makes annually where companies pay millions in penalties WITHOUT ADMITTING to any wrong doing.- Cash-for-Keys is another example of this!

If lots goes wrong, the rapid appreciation and hot market provides a good exit strategy.

As long as there are no outstanding repairs, I don't see anything wrong with paying off that loan faster. 

They are dead wrong. 

Drive slow up/down the wrong street looking like you aren't from there could get the cops called on your or worse.