Bert, when I play with a capo in the first position, I do NOT rewrite the score in transposed key; I just adjust my expectations of the open strings. For example, when I transcribed Satie Gnossienne #1, its original key is F minor. Capo at first fret, open strings are FBbEbAbCF. Well, actually I also have my seventh string tuned to low Bb.
I wanted my transcription to be in the original key, hence the capo. High F on the first string is still at the 13th fret, why would i want to think of it as an E when it neither sounds as E nor is in the fret position of E? Too confusing.
However, if a piece involved many common first position chords, then I could see the advantages of your approach.