Just a thought along different lines - to play Barre chords easily it helps if you have a guitar with low action and a decent neck profile. Some guitars have necks like bloody cricket bats; not very thumb-friendly when you play rock-style OR classical style chords.

If your guitar's got a fat neck don't go out and buy a spokeshave though - better to trade it for a slimmer profile guitar. This is especially a problem with 12 string guitars, and why so many folk buy them then give up - even after investing in finger strengtheners. For slim, easy to play guitars that are reasonably priced and great value - Norman & Simon Patricks take some beating.