Have the checks hidden, so if you fail the check, you don't even know the option exists. Telling me that I've got a 14% chance means I can reload until I get it "right", but if the topic never appears, I just continue with the existing choices. If it does appear, don't label it [Speechcraft], either; just have it happen. The RPG mechanics and "die rolls" work best when they're invisible; when the results stare back at you and laugh (like when you missed a swing in Morrowind), players get annoyed.
This is an excellent idea. I really hope they make it like this.
What I also usually enjoy are the special dialogue choices that depend on your other attributes/skills/achievements. Fallout 3 had them, but I'm more thinking of the mod "Integration" for Oblivion. In that one, you sometimes had to choose between several responses which were all based on another "achievement", and they had a tag in front of them to indicate that. However, the difference to other systems was that the full set of choices for that dialogue was always available, but there was no way of knowing if your skill, or your fame, or your wealth would be high enough to allow you to succeed. The tags simply indicated that if you choose that option, your character will try to persuade the NPC based on the achievement mentioned in the tag.
(One extreme example: There's a quest where you have to persuade a Dark Seducer to go away, if possible without killing her since then she'll only come back more angry. There is the dialogue option "[Rank] I command you to leave!", which will
always fail... unless you completed the Shivering Isles main quest. Or another option based on Conjuration, which to my knowledge simply always fails, because it's just a stupid thing to say in that kind of situation.)
I also really hope that you will be able to use Speechcraft also for "negative" purposes, like challenging someone to a duel, or taunting somebody. Oblivion was... very weird in that regard, and while Morrowind's disposition system kind of worked on its own, the game itself sometimes was just really mean to the player, on purpose. For example the Fighters Guild mission where you have to kill an orc outlaw, and the topic for that quest was her name... so you go to her, and you click on that topic, imagining how your player is giving her some speech about law and righteousness, after which she says "well you found me, let's get this over with". Instead, what happens is that she answers "Yes that is my name. What do you want?"
I want to kill you because you are an outlaw with a bounty on your head. Or at least the head of the local Fighters Guild says so, and I don't trust her, so I thought I should, like, talk to you first about it.
But the game doesn't let me do this, so my only choice is to either taunt-spam you until you finally get armed, or to start attacking you while you're completely defenseless.