It varies by situation, but a couple decent benchmarks are if it improves your rate by 1% or more, or you recover the refi costs in two years or less.

Sewer is almost always more expensive to replace than inside plumbing, because of pipe size, depth in the ground, etc.

Yes, it can feel like "wasted" money on months where rent is auto-paid and there is no maintenance to be done, but when you get a bad tenant or two or when deferred maintenance finally catches up to you, they certainly earn their keep.At your scale, you might be able to get a bulk discount with a good PM, especially if you can show how well your current systems are working and how they'd be needed less than usual.

(biggerpockets.com)Energy efficiencies in the building: Environmentally Friendly Tax Credits for Your Property (biggerpockets.com)Federal and state grants: Real Estate Grants (biggerpockets.com)On top of the benefits noted above, here are some added tax benefits from a cost segregation study: Added Tax Benefits of Cost Segregation (biggerpockets.com)Have you utilized a cost segregation study for any of these added benefits?

So not quite the same as South Florida, but I do have aspirations to move my investments south, where the commute is a little less! 

Those recently built homes start to lose value because the comparable sales surrounding them that are "Not" new builds and are selling for less causing a standstill on those new homes.

Some things to be mindful of are the added costs of having to facilitate delivery and acceptance of the windows if you are purchasing them yourself rather than go through a contractor who both supplies and installs the windows.

I'm trying to find something more durable than carpet (seems to only last a few years) and am turned off by pricing on vinyl plank.

I still have one of my two apartment vacant but the neighborhood that I am in probably has more to do with that than the Pm company. 

One flip I did, I priced with the comps but they were about 4 months old and the market had already went down so the home ended up sitting for a lot longer than I would have liked.