Adonis my man! You have contributed so much to the board and me personally. I felt I could at least share my recent experience because it related to this topic.
I started with low dose test + tren (150mg / 400mg tren), both enanthate. Results were as one would expect with that dose. I added in Ultra Rip (test prop/mast prop/tren ace) at 150mg (3x 1ml) of each a week. Dropped the test E. So my total test was back at a low 150mg/wk, total tren 550, total mast 150. I got MUCH harder looking, the mast is amazing even at that low dose. But it also killed my hairline (prone to MPB, but I didnt care). The muscle and faster ester test gave the muscle a dryer/harder look pretty quickly.
Now, to the experience more relevant to your question. I had always considered EQ a mild drug. Basically a waste of time and I always sort of avoided using it. I did not think it had much merit. However, I was getting really flat on T3 and just feeling like I was not as pumped as I had been on other runs with diet essentially the same. T3 even at 50mcg flattens me out pretty good. I added in 600mg EQ a week and was VERY surprised and impressed. It's changed my opinion of EQ totally. If you run it with high test, dbol, whatever else and are bulking you're already sort of bloated and watery and may not really see it shine. I think a lot of people who have higher BF and more water on a cycle dont really see EQ shine. You might as well be using Deca. But when leaner and/or cutting, I think its valuable. After 4 weeks, I had much better vascularity and noticeably better pumps. My cardio and endurance seemed better and I just felt a little better overall. The EQ was a great addition. I did not add any water or anything. No sides that could be attributed to the EQ besides maybe slightly oilier skin. It made a really nice addition to this stack and I wish I ran it from the start.
I dropped the Ultra Rip (tri-blend) and am now back to a simple 150mg test, 600 EQ, 200 Tren E a week. The muscle bellies are bigger and fuller than I have been this entire run and actually feel the best right now. In summary, my opinion of adding EQ in to a stack like this has changed a lot. It's more versatile than I thought and can add an additional level of vascularity, muscle fullness and pump that can enhance the look one would expect on tren/test or mast. I think it makes a great addition especially when dieting and/or flattening out on T3 when cutting.