Great post. I think one important piece of the puzzle I always felt missing while building for Mist was this that you are providing: more information on the “safe low”. Sending a transaction with too little gas is more than a small hurdle: if your last transaction never picked up, you will be missing a nonce and the next ones won’t be processed either, and tô fix the nonce issue is complicated.
On units I disagree on your suggestion of Gwei: for starters I always felt that the whole notion of gas prices should be left for advanced users and in Mist we provide an estimate of the full maximum cost of the transaction in their local currency: gas price x estimate gas cost x ether price. The only place we show the gas price, on a small box in the confirmation window, we display “ether per million gas”, which is a way to keep the ether reference in my opinion.
Other than that, please keep the great work. I’d appreciate if you could provide this information on a contract, instead of just json.