Why not ask the current bank to match the rate of the other institution? 

This way if they do not pay, you can give them 30 days notice and take the security deposit to cover delinquent rent.   

I am now being asked for an additional 30k for unforeseen complications or I can choose for them to return my deposit (2500) + 20%.At 262k my cash flow would be basically zero after all expenses (rent = 2k/month) but I will start with approximately 38k in equity (home value around 300k).Shall I sign the addendum or get my cash back?

Since they are on the hook until May, should I just use their security deposit to get house into renting shape?

Do I have any reason to return the security deposit / any defense if I choose not to?

@Alex Nicholson, do you require a deposit on your listing?

(Included in my HOA dues)*2 year deal - at the end of 12 months, rent goes to $1,900.   1st month+  $2100 security deposit.  

When studying the market rate I would focus on floor plans (match the square ft of recent rentals if possible). 

That being said, I think you can find great tenants in any area and any demographic if you focus on matching the right people with the right home.

As long as you haven't taken a deposit from them you have no obligation to them.