I'm having 3/4" x 5" solid IPE installed over 23/32" subfloor in Michigan. I have three estimates, two of the contractors would use #15 felt and nail, one contractor was no underlayment and full glue bed and nail. The reason I was given for the glue and nail was due to the 5" width which will help prevent cupping.

My biggest concerns with glue/nail is no vapor barrier, and wood splitting if it's not allowed to expand/contract during the different seasons. I will say we have a smart hvac system and does a very good job automatically controlling humidity throughout the year. Also, the basement below is a partially finished, dry and has it's own zoned heating/cooling.