...
Your customers are your best designers. (:-)
You've never working in software development have you? Most of the time, the customer doesn't even know what they actually need (or want)... Your customers are your best designers. (:-)
Personally, I don't think that we need fancy sliding bars with pretty colours... the 4 options they currently have (Priority, Normal, Economic and Low-Prio) combined with a 5th "Manual" option (probably best to be hidden by default and only enabled via advanced settings) would be my idea of the a "good" solution.
It would allow those who want to "Keep it simple" to do that... and for those that want more control to be able to specify their own level of fee/risk. Everybody wins.
Keep the existing 4 options: "Low-Priority, Economic, Normal, Priority".
In a new version include a option in the advanced settings for a fifth option "Custom" or "Manual" (prefer Custom, sounds better), where you can set your own fee as "satoshi/byte".
Very good idea, would really like to see that option in the next update.