No heat problems because of the exhaust manifold. When I change my oil the by-pass filter does not seem to be any hotter than the OEM full-flow oil filter. I let my Cummins cool off for about 10 minutes before removing the filters, really no temperature difference.
I drive in a lot of stop-and-go traffic in the Dallas/Fort Worth metroplex; everything seems OK. Ideling might be a problem, but of course extended idle may void the warranty... ... ... ... ... (hehe).
I was concerned about the heat at first and after running it for a while (5,000 miles) I checked the return flow to the top of the valve cover to see if it had changed at all; that is the heat somehow effected the filter media. It looked the same. As mentioned above, there is not any discoloration of the paint on the by-pass filter.
So, I just keep movin' on.