I can't see much to be gained by going up. I think it would do a lot more for Bruce's performance to stop going top speed through the likes of Trooper. I don't think he lacks the high notes, but unnecessary speed for the sake of 'its that whole live Maiden experience' has him tripping over himself. Arguably, quickfire vocals have always been at odds with his singing style, he thrives on longer notes and pauses in the right places. Some older songs might be slower than they were in the Maiden golden age, but some live songs are slightly too rushed for a top quality performance. I was a bit sad that they compromised on the performance quality of If Eternity Should Fail - which at album speed is highly suited to Bruce's vocal performance and makes for a very strong opener as it is - either for the sake of cramming more stuff in, or (personal suspicion) because heavy metal kudos apparently requires speed, and they wanted to make more of an impact with their opener.
I'm inclined to agree with the suggestion that Maiden can sound muddy live. Too much emphasis on a wall of guitar sound with the singer contending to shout over that. I don't 100% mind that effect when it's done well, but it's possible to overdo it live and practically drown out the vocals, as I found at one performance in particular in 2017.
And I do wonder at times if part of the tune down sentiment is less because of actual problems with Bruce's voice, and is more because people have become accustomed to hearing metal with very low tuning, and everything in standard tuning no longer sounds 'heavy' enough.