Many are suggesting that EDMs need to be reformed rather than scrapped.
I have nothing to say on the cost or efficacy of EDMs as they stand beyond James Graham's view. However I do worry that, if badly done, electronicizing (?) EDMs would effectively neuter them. Part of the point of digitizing (that's better) things is that they become cheaper, easier to use and easier to maintain. If setting up an EDM became easier than it already is, then it is inevitable that there would be more of them, and more of them would be signed by more MPs.
Therefore, in order to be seen as worthwhile, an EDM would have to attract a considerably larger number of signatures than they do at the moment, which means that more MPs would spend more of their time ticking boxes and signing them.
Eventually, I envisage a situation in which there are 10x more EDMs, each with 10x more signatures, with MPs spending exactly the same amount of their time signing them, and the Commons spending the same amount of money maintaining the new, larger database.
Perhaps I exaggerate, but I hope you see my point.