It would seem to me that if something like this is implemented, it might be better it it was displayed automatically. The last thing I would think an IFR pilot should be doing when going MA, would be to be punching "buttons" on a VFR only device.
Which brings up another thing. As I recall, altitude guidance ends somewhere around 250AGL on any approach. It would seem the same restriction would apply for departure. It would seem iFly doesn't want us to rely on it for (potentially IMC) altitude guidace below 250AGL.