Just to follow up on this, I upgraded from my smaller OS 80GB SSD to a newer 120GB over the weekend.
Used EaseUs todo backup and partition manager to achieve this.
Installed the new drive, and used the partition manager software to create a useable partition on it. It didn't come with one pre configured.
Then used the Todo backup software to clone from the old drive to the new drive.
This worked, but left the new drive partitioned only for 80Gb, so an exact clone of the old drive.
Then fired up the partition manager software again and dragged the 80GB out to the full 120Gb of the new drive.
All sorted after that.
Quick and easy with those two software products.