I have tried the porche pipes too, and they don't do much to smoke cooler than briar. The original ones that had the matal radiator fins did help somewhat.
There's always the Spanu cork covered pipes. They're suppose to be cool smokers.
I was talking to Dave Wolf of Briarworks yesterday, and although my questions were about what causes one pipe to gurgle more than another, his answer, which I will include here, also refers to why a lot of pipes smoke hot. I thought it was interesting.
"Thank you for your email. 95% of the time, gurgling is from a poor airway. The airway from the bowl to the of the shank should be 5/32" in diameter. A good percentage are, a lot are not. The problem then is the diameter transition from the shank to the stem. Problems arise when there is a relatively large shank airway that goes into a relatively small stem airway... quickly. That's kind of the principle of a dehumidifier in that moist air (in this case, tobacco smoke) is sucked or pushed through a small hole. Moisture is squeezed out. In a dehumidifier, that's a good thing. In a pipe, the moisture builds up creating a gurgle. In pipes with very small airways, the additional "sucking" in order to get smoke through accentuates the problem.
The solution is to either make sure the shank diameter is 5/32", or open it to that, Second to open the airway in the stem as much as possible without compromising its' structure. Next, and probably most important, it to chamfer, or funnel the end of the tenon so the transition from the shank to the stem is as smooth as possible.
I actually open and/or correct airways on hundreds of pipes over the period of a year. I do it more for hard draw problems and a hot smoking pipe than for gurgling, but in every case the gurgling, or wet smoking pipe problems go away, sometimes much to the surprise of the pipe's smoker. If you have a pipe that "just doesn't smoke right", or "tastes bad" or "smokes hot", the airway is usually the problem, not the briar, the pipe or the tobacco. In a perfect world, you should never have to use a pipe cleaner to sop up moisture when smoking a pipe.
Here is a link to the "Fixing Meerschaums" page on my website. I chose to write about Meerschaums as they are extreme examples of crappy, tight airways. The same principles exist in much the same way with briar pipes. At the bottom of that page you will find a link to an excellent article written Ken Campbell that expands on everything I've said here."
Personally, I have a number of pipes that have straight grain, and a few have really gotten hot, but I think it's the way I smoked them. I don't think that one type grain smokes any cooler than another. But I have an open mind on this subject. After all, it's about having the most enjoyable smoke posible.