I've never used the music minus one series, but this is the best (albeit the most expensive) way to learn a concerto, I think. It works best if you are connected to a good music library, and if you are learning well-known concerti, which these two definitely are. Get a two-piano version to learn it, and afterwards check out a full score and begin to base your more advanced interpretation around this. Also, listen to as wide variety of recordings as possible. This will prevent you from getting too attached to one, and will allow you to understand better how the orchestra and piano interact. Then, also, as you practice, particularly if only providing support, try to "hear" the orchestral parts. If possible, sing or hum them during accompaniment, following that line in your score. Have fun!