IMR4350 was my go-to for my 30-06's and 270's for decades, delivering excellent results. Velocity was rarely stretched with accuracy/precision looked at as the primary consideration. I never experienced temperature sensitivity issues perhaps due to the short-medium range distances they were tested and used. When I started to hunt/compete at the longer ranges, velocity/ES, temperature sensitivity, cold bore accuracy, etc. was far more critical all for long range performance(1000 yards). I found that H4350 for small capacity cases(ie. 260R, 6.5x47L) and, H4831SC for larger case capacities(ie 6.5x284), gave exceptional accuracy, optimal case fill, low ES/temperature stability, and cold bore accuracy….Conversely, since the Obama era shortages for which the H powders were in short supply(with some still hard to find today), it was a struggle to achieve all these characteristics with the IMR powders for these cartridges. Perhaps I could have gotten there with the IMR powders with additional load development work but it seemed far easier to hunt down the powder…which I was/am usually able to do. IME, the "H" powders(including H1000) have generally been some of the easiest, and most consistent powders for me to work with for precision shooting…