aneirin wrote:It is not so much the high rolls that bother me, it is the chance of failure, how often someone rolls under 12. It doesn't seem to happen a lot and success seems guaranteed in many cases, unless an unskilled person tries it. But a party will always send a skilled person for the test. The only way to bring failure into it is to orchestrated it so people take checks.they aren't trained in. Or to day to every test, oh, you need two degrees for it to do what you want rather than succeed. After all, the stories are all about people failing! I want more failure

And a bonus die isn't really a plus one, with 4 test die and 2 bonus, you have a very high probability of a one and a six, leading to a maximum plus 5 and a very high chance of a plus 1. With.there being an equal chance of getting a higher number and taking into account that you may not roll a one, bonus die are closer to giving plus 3 or 2.
4 test die average 14, with two bonus die you are looking at 19 to 20 which gets very close to heroic. People are looking at doing heroic actions.close to half the time, or possible half with modifiers. (though may need a statatician to work out bonus die bonuses as I am sure more bonus.for would provide diminishing returns, each die providing less of a bonus.
Actually, the best chance you have for your players to fail is to challenge them at their weak points. I love doing that, but that's also because of my bias towards well-rounded characters.
Don't forget that not every difficulty is 12. Don't be shy with modifiers or simply raising the difficulty when it's called for. Sure, an athletic PC with Athletics 4 might have little trouble jumping from one roof to another in clear conditions.
Try doing that at night, with a half-moon, raining, and while he's being peppered with arrows.
That's what stories are made of.
BTW, MERP sounds totally needlessly complicated and counterintuitive

Again, kinda biased, but with plenty of proof. If you like different dice types, try Savage Worlds- it's a lot like the CORTEX system.