Partnerships can be quite difficult. I entered into a partnership with an agent in my office with similar experience as myself and hoping for accountability, energy and efficiency. We spent countless hours working on incorporating our business plans, hiring an assistant and hashing out the fine details. We felt our partnerships would incorporate each others strengths and support each others weaknesses. We had limited success, but what we didn't count on were our differences of personality. It was like a marriage to someone after only knowing them for a short while. We were great on the surface, but behind the scenes had such different goals. That is what ultimately prevented us from having a successful partnership.
In your case it sounds you have a thriving business with systems in place to both generate and handle the business. My suggestion is to speak with some other partnerships, whether in your office or at other offices, and see what makes them successful and what their pitfalls have been. Because you are the experienced partner bringing most of the business and systems to the table, you are more than likely entitled to a higher percentage. This is something you will have to discuss with your prespective partner and see what is fair and amicable to each. There are so many logistical hurdles you must overcome...Will you be splitting all your business including past clients and sphere of influence? Will you split the costs/fees equally? How will the names be on all your marketing material? How will you handle listing appointments (who talks)? Who will be the contact person for current clients? I'm sure there are a ton more questions that will need to be discussed. If you are looking for more time off, perhaps a good assistant might work. If you are phasing out of the business, then a partnership might be ideal.
All the best,