The advantage to the collection agency compared to a judgment is time. What is your time worth and how much money will your business lose by pursuing a small claims judgment?
If you decide that time is not an issue, getting a judgment is a very effective way of collecting money that you are owed.
If they own the building they are in, you will be able to put a lien on that building (filed almost automatically in many jurisdictions). This, in most circumstances, will prevent them from selling or refinancing the building until your claim is paid, plus accrued interest. However, it may be several years until happens.
If they do not own the building, and they are simply leasing it, they have likely paid a security deposit on that building lease. You would be able to attach the security deposit that is being held by the building owner. You can determine the building owner from the county assessors website.
As a real estate office, they obviously have a relationship with one or more banks. Sending a writ of attachment to their bank can very quickly get your judgment paid.
In addition to the small claims route, you may be able to lien the property as a contractor. The laws regarding this vary by state, but is generally very easy. Many states have very strict time requirements, and you may be outside those deadlines.
If you are not familiar with the contractor (or sometimes mechanics) lien laws in your area, and want me to see what I can find out for you, send me a message.
Something to consider. When they are served with the lawsuit, it is very likely you will be paid right away. Real Estate companies are not the most popular right now, so having a judgment entered against them could damage their financing relationships, and they know that.
This posting is general in nature and should not be considered legal advice.