really good but short life span

I play a 1910 austrian parlour guitar and the gigs I play are usually 4-6 hours of playing straight with mostly alternating bass chord accompaniment. For my instrument and style of music I play (1930's rembetika) these are by far the best strings I have found and I have been using them for about five years. However they go through several phases before they die. First 1-2 hours of playing, very bright, almost sounds like I am playing on a piano, 2-8 hours perfect, they mellow out a bit and I feel perfect control, 8 hours......they die. I have to change strings every two gigs, if I don't change them before the third gig I am embarrassed by how dull my guitar sounds. They also break very easily, depending on the humidity and temperature, on a cold humid night I can start breaking strings about 3 hours into playing having changed strings right before a gig. All this said, for those 6-7 hours when they are in their prime, I have not found a better set of strings in the market.