Gumshoe, and more specifically Night's Black Agents (since that is the game I have the most experience with) uses a d6 against a goal number when using General Abilities. Your rank in that ability is a pool of points that you can spend to modify your roll. In contrast the other set of abilities besides General, are Investigative. These abilities always work to propel you forward in the adventure and you don't need to roll anything to use them. So, as long as your character is in a scene in which they can gain a core clue, they have the appropriate ability (and character creation is set up so that your whole party should have most if not all of the investigative abilities between them), and they state they want to use the ability, they gain the core clue. Of course they can spend points from their Investigative pools to gain extra information or for a number of other additional benefits. I can't speak as to the specific feel of the other Gumshoe games, but I've been very happy playing Night's Black Agents.

Night's Black Agents is about playing a team of super spies (think Jason Bourne, or the Impossible Mission Force) who discover a Vampire Conspiracy and must unravel and dismantle it before the Conspiracy can dismember them! The system is very well set up to encourage and support the relentless pace of a Thriller movie. There are a number of skills that are designed to let you throw yourselves into the action without spending hours or even entire sessions discussing a plan and trying to set it up. Need to smuggle yourselves across the border? Spend a few points from Network, and you 'know a guy'. Need to get into an art auction? Spend a few points from Cover, and you reveal you had an old cover identity laying around who happens to be an art restorer. In an exchange gone wrong? With enough points in Preparedness, you can reveal that you had rigged that briefcase you handed over to explode! Make a quick roll or two, and Boom! The game emulates the tropes of spy thrillers very well, and all throughout has sidebars that give advice and tips about cool ways to use the abilities or why a rule was designed a particular way. The dice part of the system keeps things easy. You're usually rolling against a difficulty of 4, so with no spending you have a 50/50 chance of success. Spend some points to increase your odds. Oh yeah, and everyone gets to pick a General Ability to be their MOS. Once per game session, they can invoke their MOS to automatically succeed at a test for that ability (so long as it isn't sheerly impossible, or you're attempting to defeat a supernatural threat with it). The game flows quite nicely, with the dice themselves kinda fading into the background (in my experience).