One of the things that the roll and keep system introduced to our group was the idea of raises, deliberately increasing your own target number in order to get better results. It was revolutionary for us at the time. All of us had grown up looking to see of that magical "natural 20" popped up on the attack roll, and while other games, among them Shadowrun, had long ago introduced the idea of incremental success, putting that power in the players' hands was wholly new. Needless to say, my group took to it immediately.
The problem I've had with it as a GM is that players often refuse to stop when they hit their target number. When rolling 5k3 and looking for a 15, it's been my experience that they'll reroll every 10 they get and tabulate the result all the way to 63, even though all they need is that 15, and in fact it doesn't matter mechanically if they rolled 15, 16, 63, or 163. Hit you TN or don't. All that incremental stuff got taken care of when it came time to raise.
I get the thrill of the high roll. Really. It doesn't happen often, but I do occasionally play an RPG instead of run one, and my luck with dice is such that any time I break into double digits I'm elated. So I do understand how awesome it is to roll high. But the thing is that it takes time to tabulate those towering results, and if you already know whether you've succeeded and how well, everything else is wasted time. I've tried to push on as soon as I know that the player made the roll, but I've actually been shushed with a "I'm not done yet!" before.
And then there's the fact that even though the roll and keep system has been around for a decade now, it's still close to unique, which means that my players consistently forget to do it because it's unlike any other rule they're exposed to. This often leads to much head smacking and cries of "I should have raised," right after the dice clatter on the table.
So I took a page from one of Mr. Wick's more recent games: Houses of the Blooded. In this, there's a still a raise mechanic. It's called wagering, but in effect it's the same thing. However, instead of inflating your target number, you remove dice from your pool. Your target number remains unchanged.
I began using this rule for a few reasons:
First off, it keeps target numbers low. The average target number is 15, and it's always 15. You want to raise 5 times? Drop five dice out of your pool and look for a 15. You don't have to calculate that 5 raises on a 15 makes the TN a 40, and then begin adding your dice toward that number.
By extension, it makes high raise rolls faster, not slower. Since a pool in which you made a lot of raises is now smaller than normal, there's less dice to count. And my players like to raise, a lot. They're good at what they do (by my design; I prefer stories about competent heroes, not bumbling idiots, though I do know some people who prefer the latter), and they want to show it off. It's not unusual for them to call 4 and 5 raises in their area of specialty.
By requiring the player to modify his die pool before he rolls, it places the focus of the raise not on an abstract target number, but on a collection of dice he holds in his hand. Every time he picks up those plastic bits, he's got a physical reminder to raise. Since we've switched over to this method, some players have complained that they didn't raise high enough, but no one's forgotten to raise on a roll.
Finally, and this is purely a taste thing, it places a limit on raises. I don't have a problem that 7th Sea lets people raise to the heavens, and sometimes I even encourage a little outrageous raising as the GM. However, this particular campaign swings back and forth between two tones. Most of the time they're galavanting about the globe on missions for the Explorer's Guild. However, they're actually members of Die Kreuzritter, and they occasionally have to bury artifact finds or make scholars hewing too closely to a dangerous discovery disappear. More than that though, they've discovered some cult activity that's far more sinister than the typical Legion cults. These cults have sporadic appearances in obscure historical records, such as an ignored field report found in Explorer archives about something called the LeGrasse expedition to the Midnight Archipelago. It seems LeGrasse encountered natives performing blood rites while chanting about something called Cthullhu, or R'yleh, or something like that. My own party stumbled onto this only after rescuing someone from a group related to some sea beast called Dagon.
I do love me some near-super swashbucking action, but when horrors from beyond time and space begin to creep in, I like that the die drop method of raising places some mortal limits on the players. It's something I can play up as they sink deeper into the horrors they uncover in an attempt to protect the world.