Seems I have heard that the 748 is not good for high temps. The powder is to be the same thing as BL-C2, so load data should be very comparable. If this information is correct the Winchester powder is a little more refined than the H BLC2 and the benefits where to be cooler burn like you stated.

The H4895 might be better for temp ranges than its sister IMR but you did not mention the availability. I am making the switch myself and will be experimenting with the H4895 soon. Good luck and keep us posted.