But a co worker who has a construction background said it would likely cost much more.

SF does not have a co ins. penalty (i.e. many companies penalize if you insure for 60% or less of rebuild cost, or something of that nature.

I don't personally have experience but reviews on the interweb and speaking with a co-worker who used them make it sound like its a durable/cost effective solution to extend the life of those surfaces.

You also want to screen the co-signers too, because having a deadbeat as a co-signer is not worth all that much.Sounds like belt and suspenders, but ...

The other party could be a co-investor, it could be a seller who you want to offer seller financing, it could be a banker.3.

A co worker of mine had a landlord who did that and I hear all day long that his landlord is home cooking all day for his big family and splits the gas bill with him 50/50.

Co-sponsors - This is a team sport, so you would want a partner(s) that has complimentary skills to your skill set.  3 things your team needs to be really good at to be successful:  Sourcing deals, raising capital & asset managementIt helps to have a co-sponsor who can serve as the Key Principle to be underwritable for your loan (depending on the size of the deal)Someone with experience and a proven track record of success syndicating multifamily dealsattorneys well-versed with syndicationI would pay attention to what the attorney's say when you are interviewing for your legal team. 

But in work we work professionally as a co-workmate and not as a married couple.

I have a quick question I recently purchased a Co-op in the NYC area.

When we are landlords we see how other people live, verses other people who see each other only as a friend, or a co-worker or an occasional acquaintance.