This being said, rule sets are not interchangeable (this, as my college physics textbook says, "is intuitively obvious to the casual observer"). Some rule sets better support tactical choices in combat while other rule sets support quick play and exploration.
Of the three, extraction seems like the least affected by the rule set used. This leaves exploration and encounters. Of these two, encounters are directly impacted by the rule set used while exploration is indirectly impacted.
This is not the case with encounters. Assuming that most encounters result in combat, then the speed in which a rule set decides an encounter determines how much time is spent on the encounter. Simple, abstract rule sets, like Swords & Wizardry, have short real time encounters. More complex tactical rule sets, like GURPS and Pathfinder, have much longer encounter resolution times. On the positive side, these rule sets offer players and GMs plenty of tactical options (I am true fan of GURPS in this regard). The down side of this tactical richness is the time it takes to resolve the encounter.
What this means for the 4 hour gaming session is that, with a more complex rule set, more time is spent on encounters. By default, less time is spent on exploration. Reducing the number of encounters is the only clear way to mitigate the impact of a tactically complex rule set.
This is where intent comes in. If the GM and players have a common intent within the dungeon campaign, then it becomes much easier to be select a rule set and, more importantly, be content with the strengths and limitations of that rule set after many sessions of play. If the intent is to maximize tactical choices for players in a dungeon setting, then GURPS is the way to go in my book. If the intent is to maximize the amount of geography covered so that it is feasible to explore a really really big dungeon, then a simpler rule set like Swords & Wizardry Core would be my choice. In each case, GM and players have to be content with what they have and also what they give up. After all, it is entirely possible to revisit the same dungeon with a different intent and rule set.
I have been thinking about rule sets and intentionality from time to time, just because I think about things like this. More recently, I have been thinking about this since we have switched to D&D 5e. It is a slick, well-designed system...I like it a lot. However, it is slower than Blood & Treasure, our previous rule set, when it comes to encounter resolution. In turn, this has taken time away from exploration. And, D&D 5e doesn't have a lot of tactical crunch in combat, thus leaving our tactical crunch guys yearning for more. There is a lot of out-of-combat decisions that the players must make--which was one of the goals of D&D 5e (perhaps the subject of a future post).
As for me, my intent in creating the Montporte Dungeon was to focus on exploration, by creating a huge dungeon that would be too big to completely explore. And this dungeon would also have lots of connections to the Deep Dark...more connections to what lies below than to the surface world.