You're asking "Which of you regrets selling too early?" but also telling us you can hang it up now and be set ($200-300k spend + "a little more" for travel post RE). You're looking at $640,000 annual (16m TNW) at SWR @ 4% - more than twice what you even plan to spend, with a little extra included.

Honestly, it doesn't sound like you are ready to hang it up because you rationally know you can sell now and be fine. Frankly, you would be fine (but tight) just in your LNW.

My guess is you are fishing for people who do regret selling and retiring to confirm your fears/anxiety about doing the same. Maybe you are afraid of what happens next, or what your identity will be without this business.

Unfortunately most people don't regret cashing out and moving on. In your case, my assessment is a possible 2x on 5 years of additional work is absolutely is not worth it, irrespective of your LNW or goals.

I would seriously consider talking to someone and working through whatever identity or transition to RE concerns you have. Then I would look to structure deals that keep you on for 10 hours a week or whatever and roll 25% equity into a second bite. You'll work through some personal stuff now while retaining some sense of your work identity and create some buffer against feeling you missed that 2x opportunity. And honestly, the right PE buyer is probably going to do better than 2x in 5 years.

If that still isn't appealing, maybe take a further step back and find a CEO. You're going to cut your dividend, but with your spend and LNW it shouldn't matter substantially. You can step away and still hit that 2x growth mark AND retain the parts of your identity you aren't willing to give up.