So, I'd be a designated rental tank user as I only have single tier X tank, the Kranvagn. During the Dynasty Wars I played all the BB tanks, the UDES 15/16, the WZ-111 5A and the Object 140 became my favorites without any doubt. In fact, I could even claim my first tier X mark of excellence on the 5A BB where my damage standing is 73% as of now (I'm fully aware that the expectation values are very low).
Now, my biggest issue with the BB tanks was that I couldn't use my regular crews without retraining them. As it was a longer event, I did retrain my UDES 14 and T-34-85 crews completely with gold, for the Pz VII and Progetto only the commander (also gold) and for the 5A I used the crew it came with and used boosters, 6th sense directive until I trained 6th sense on it (and I'm 80%+ into the second skill).
I hoped that WG would come to their senses as they did in the Frontline rentals like the T-44 FL and the T32 FL where you can use your normal Russki medium and Murican heavy crews and the next rental tier X tanks would be similar ones. However, the WZ-111 5A BR and Object 140 BR need their dedicated crews again – even though, they are essentially the BB tanks. How do I know that? Because they show up in my service record and the 5A BR has that one MoE, they show how many battles I played in the BB tanks, win rate etc.
After the BB tanks were removed, my 5A BB crew became a 5A crew, meaning if I put them into the 5A BR, they would be penalized. With all that said, I may play maybe a single battle in my Kranvagn but that's all. I can't spend another 1600 gold to have my multiskill crews move back and forth for a weekend event and I'm not gonna put my team to a distinct disadvantage having bad crews at tier X. Tank Brawl would be a great idea, I even would use some gold to demount equipment for the rentals but this way I'm gonna skip it.
TL, DR: I like the rental tanks but hate them that I can't use my regular crews without penaly like I could do it in the Frontline rentals. Same issue I had with Dynasty Wars.
PS: my BB experience and results: