I think that this answer can be split into a few parts.
1) Outriggings
You see them everywhere: material is used (within the "box" so to speak) that folds out once the match starts to allow the robot to maintain balance and defend itself from tipping. I feel that these are appropriate as engineering aspects of the robot and should stay. Also, it's hard to decide how you'd regulate them.
2) Sloped sides
Many of the effective bots I've seen this year had sloped sides that helped with both the balance, defense, and overall imagery of the bot. An excellent example is 67. I assume that is the type of the robot you mean, with a base geometrically designed for that kind of balance. I think these are appropriate provided they remain within the box, which 67 among others does uniquely. I know there were a few bots that didn't pass inspection with their riggings and slopes. Since there are rules against ramming/spikes, it'd be good if you could explain the connection you have here. I think that's the main concern, but I'm not sure.
3) "Ram" sides
Some sides are designed specifically perhaps to throw other robots off balance. It is an offensive tool. I don't feel comfortable making judgement on a team for that strategy. As far as angle goes, what is appropriate, and what isn't? I think you have a few good ideas here to keep things flowing well on the field, but at the same time it adds a whole new aspect of change. I think that in 2006 the game will be designed to address this structure interest, and robots will be built and geared to it.
Good luck with considering proposing this to FIRST rulemakers, if you choose to. These are just some thoughts on the subject.