1. You are probably better off selling a bike that does not meet your wife's needs and buying an appropriate one than you are upgrading. That is true both from a money and time/effort perspective, especially if you are not experienced at sourcing compatible parts.
2. Bike weight has very little impact when you are talking about differences of a pound or two, or even more. Remember that the bike's weight when ridden includes rider weight, which greatly lowers the percent difference in weight. On top of that a 2% weight difference (ex: 4 lbs off of rider + bike weight of 200lbs) is less than 1% impact on speed/effort.
Last edited by cny-bikeman; 09-01-15 at 11:07 AM.