I tend to use my TR’s for basic stuff word internet etc and have desktops to do photo editing etc so I’m not really best qualified to say if 1.5gb over 1gb of ram would be worth it. At the current cost I’d personally say no, because if it were cheaper I’d put 2gb in mine, after all more ram will never hurt.
My personal opinion of the TR series is it’s mainly processor & bus limited, so ram alone wont be a huge improvement.
If you haven’t looked yet see the SSD topic. I recently fitted a 16gb SSD drive to a TR1mp and it really has transformed it. SSD drives are to small capacity and too expensive for most now, but it may be worth saving up for one as prices should drop in the new year. It’s also an upgrade you can move on to the next laptop if you want
Sony TR with SSD future dream?