The likelihood of a challenge on that alone is almost negligible.

I also left a bucket of salt and shovel for the tenants, and they have been using them.I was finally able to speak to the tenant, she informed us that she has already been talking to her lawyer, looks like I will have to file an insurance claim :(  Not sure how this will play out, I wasn't negligent in keeping the property clean and resources available for tenants to prevent slips and falls.

I say that only because -400 versus -600 is negligible. 

However, for future tenants, I would like to shift the cost of their negligence to them instead of being responsible for it myself.I've done a bit of research into sub-metering in MA (http://www.mass.gov/courts/case-legal-res/law-lib/...), and it looks like the only requirement is that I also install low-flow toilets/sinks, etc.

A customer sued the S Corp for negligence, along with the husband and wife owners, a lawsuit for several million dollars.I spoke to the manager of the business, whom I kept on, he heard the owners as individuals worked in the business as individuals, and they're sued in their individual capacity as managers.

So long as you are not committing any grossly negligent acts and you have a decent insurance policy the risk of owning a small property like this in your own name is very minimal IMO.

But as I'm looking over the mortgage disclosures for our next purchase, I'm wondering if I should do just that.Right now, $5000 would be very helpful to have in my hands instead of in the check we give to the title company, would probably raise the monthly PI about $30, and would have negligible impact on my performance numbers on this house.  

T also liable if T or T’s guests willfully or negligently cause violation.

If something were to occur a 3rd time, in my opinion, this would cross from a gray area to negligence on my part (with the exception of a severe storm or weather event similar to the first storm).

First of all, your realtor is either negligent and/or incompetent, neither is a good option.