Water can transfer heat around nine times faster than air. So, wet heat is way more efficient than dry -normal- heat, but 'opening the pores' isn't an extra benefit. Ultimately since the penis resides outside of the body and provides enormously more area for the application of heat, faster than the attachment point down at the base can help shed the heat away, really any manner of heat is going to warm the entire organ pretty quickly.
Wet heat can accomplish that a bit faster, but if the wet heat source loses its warmth before you're finished, or is only being intermittently applied between massages, then you're left with a wet penis which will tend then to get cold very quickly through evaporative cooling (that's how sweating works to cool you off) .. so wet's advantage can also be its liability.
If you want to go beyond even wet heat look into FIR .. far infrared therapy. Far Infrared penetrates more deeply into the body than even wet heat for the purposes of most therapy. And while any kind of heat will warm the penis up in a similar manner, Far Infrared also has some impressive anti-inflammatory properties (heme-oxygenase-1 etc, catalytically active enzymatic agents that specifically speed healing in bruising) which wet and normal-dry heat do not.
In fact .. to make a distinction in the terms .. using (per se) -heat- too soon after your tissues undergo a stressor can impede healing by causing unnecessary extra bleeding in the affected tissues, so keeping in mind the distinction between 'warm' vs 'hot' .. don't use so much warmth right after a workout that it becomes hot .. that could have the opposite effect that you're looking for.
tempted to do some more 
