I've toyed with changes to Feint before several times.
I've also toyed with the idea of using the TDM table - the often-overlooked heart of GURPS modifiers - as bounding the limits of penalties.
Here is an idea I had - but have not yet tried - that could apply the TDM to Feint.
First, a cap to Feints/Beats/Ruses, and a bone to throw to people who feel hurt by this.
Feint Effect Cap
Feints are resolved normally; however, the maximum penalty to defend that can be inflicted with a Feint of any kind is -10.
Why? The idea here is to apply an upper boundary on the useful levels of skill and defenses. Plus -10 is already harsh, it doesn't really need to be able to go to -11 (or more) to be harsh.
Someone with Skill-30 still has the ability to utterly crush a foe's defenses - you can put someone to -10 easily with a Feint roll and then smack them down another -10 for Deceptive Attack if you really want to and hit 50% of the time, or take the foe to -17 and have a 98.1% of hitting. Skills above 30 really don't make much sense - Sure, you get Parry 18, but the most a foe can do is put you down to 8 via winning a Feint and then Deceptive Attack you down to nothing by taking a big penalty.
Even a 30 is pretty ridiculous in this case - while penalties are easy to come by, and it's still useful, it's not the skill this was design to deal with. Even a 20 skill can put someone to the maximum penalty. As I've mentioned, players like maxima. Knowing the worst-case scenario and best-case scenario for a "featureless plain" duel means you can more easily decide what skill you need and how much defense is probably enough.
Personally, I like the idea of this - especially in the game I run now, where PCs have routinely crushed foes defenses or face ones who can have them crushed below a rollable number. Why do I need to roll for the orc's Broadsword-13 against Borriz's Axe/Mace-30 or Vryce's Two-handed Sword-27 when the latter two roll a 12 or something . . . I can just say it's at the max -10 and move on. It doesn't need to be worse, and the idea that -10 is as bad as it gets is solidly GURPS 4e.
Of course, some people hate caps and limits that didn't exist in the game. So here is another idea, which might make a nice way to give on one hand as you take with the other.
Critical Hit on a Feint
When you roll what would be a critical hit with a Feint (a 3-4, a 5 on skill 15+, 6 on skill 16+), you also hit your target with a normal attack if you wish to. Decide when you roll the critical. Hit location is random, and attack type can be any allowed (choose before you roll location.) The opponent defends normally - this is not a critical hit. However, if the roll would have been a Critical Miss (17-18, 18 on skill 16+) go to the Critical Miss Table as usual. Resolve the Quick Contest of Skills as usual.
Why? It's a way to fold in something of a Setup Attack without actually implementing the rules in Delayed Gratification, it's a way to give back if you're capping Feint. It also stops the endless groans at the table when someone rolls a 3 on a Feint and says, "I should have just tried to hit him!" Well, yes, that's still the case, but with this rule you got a hit and a Feint instead of just a hit that couldn't be defended against.
As noted above, I haven't tried these, but I do really like the bounded limits of the TDM table. I like the bounding of effective utility of Feint and applying soft limits on useful Active Defense levels. I also like the idea that a really good Feint can slide into a full-on attack if you're both good and lucky yet still leave the opponent open for the next. I'd be game to try these out if I can think of a way to smoothly do them without adding more time-per-turn as people consider Attack vs. Feint and so on.