Anyone have experience with buying out an equity investor which a minority stake (20-25%)?

I'm looking to hear from buyers who bought a business in 2 tranches, where the first tranche involved an equity investor and a personal equity investment. I am considering a $4MM deal and buying 45% of the business so that the seller can stay on board for 2 years and get closer to the exit price the seller wants, and I agree to pay. I would have the right of first refusal, and this would be a stock sale. There would be a second sale at a revenue target or within 3 years where I would buy the remaining 55% of the business and use an SBA 7(a) loan for this acquisition. Would love to hear more about your experience and any insights you can provide!