Another Overnight mashing question

I use a digitalized temp controlled commercial coffee urn to mash in. I can set it to any temp and it will hold at that temp perfectly for as long as I want. I'm thinking about trying an overnight mash, just to see how it would work. I have two questions that I would like to hear your opinion on. (BTW I'm thinking about making a English Brown ale or is there a style that might be better)

First question: I can mash-in at my target temp and it will hold indefinitely, or i can mash-in at a lower temp and it will slowly increase until it gets to the temp i want it to hold at. From a protein rest at 120 something, to conversion temp at 150 something, it takes 2 1/2 (plus) hours to get it to stabilize. Should I go right for my target temp, or let it climb slowly? What do you think I’d have the best chance of having the best results?

Second question: What would be the best target temp for conversion overnight? lower 150's or upper 150's. I can hit exactly any temp.

Thanks in advance!

While not exactly the same, I do direct fire BIAB mashing to raise the temp. I get around 80% eff.

Despite hearing all of the calls about this will ruin head retention. I do not have this problem.

For the temp question. If you want it drier than hold the temp lower, sweeter then mash higher.