I understand as they want to retain control of the listing but on the other hand, they are wasting their own time in fielding the calls and questions that would naturally be asked.Back to the OP's question; from my experience the information provided varies greatly.

You may be able to retain the management (if they're good) which is a bonus as they will know the property. 

These three pieces of advice are all designed to retain tenants as long as possible.A little more on each...Most of my tenants are on their 4th or 5th year with me.

@Francis Rusnak, I agree, always retain an attorney for a closing in Illinois.

Is it worth the potential income loss to retain these long-term, responsible tenants, or should we consider bringing in new tenants at the higher market rates?

They just put me in contact with their lawyer who required a retainer just to initiate looking into it. 

We are both married, have mortgages, brokerage accounts and now with the business (expenses and set up costs) going forward we thought it best to retain a CPA for the coming tax season.

Aside from time and labor I now have nothing invested, even will get $7k additional back and retain $57k in equity.I’m not going to throw out cashflow numbers since everyone tends to calculate vacancy, repairs, capex differently and I don’t want to get off track.

There aren't caps on STRs like there are now in places like South Lake Tahoe or Palm Springs, but there are still some legal hoops to jump through.I believe urban markets tend to be less friendly to STRs, as the housing is generally more regulated and neighborhoods have an interest in retaining long-term residents vs. seeing people come and go on a daily basis.  

I found a really good attorney with no retainer fee who’s great for bouncing ideas off of, PM me if you might need the reference.