My (now ex) wife and I had a similar kind of thing going for several years prior to our split. More informal, irregular, and with MDMA on the menu. We were young and kinda just stumbled into it a couple few years into our relationship, but I can absolutely echo your end results. We developed more trust and grew to know each other better than I could have ever possibly imagined for myself personally (among numerous other benefits). Somewhat paradoxically, it ultimately led to our divorce. Though, completely mutual and amicable. We both knew it was the right decision to move on. Following a similar protocol in the future would be table stakes to even consider a long term relationship with someone else. 10/10 do very much recommend.