Also have a look at this.
Once of the student who was on IGS won an appeal on the basis that you dont need £800 at all when you go from IGS to PSW. Follow the link for details.
http://www.gherson.com/News/Ghersonsucc ... ments.aspx
"If you have valid leave to remain under IGS or SEGS on or after 30th June 2008, you will be able to apply to extend your permission to stay in your existing category. You will not be required to meet the points requirement if you are applying under this transitional arrangement. You can apply under these transitional arrangements at any time from 30th June 2008. If your application is successful you will receive an extra year from the date your visa is due to expire."
So maybe the argument will shift from not meeting the maintenance requirement to not needing to meet it to get the visa! I just knew that something went wrong from the time the so called "PSW forms" and the "Guidance notes" were printed... there was a gaping omission...it only made the the most perfect sense to extend an IGS no questions asked - because we didn't have to do that initially and so a concession was made for us...however it was omitted from whatever half-baked guidance that was given to the Home Office case workers! They see no difference between students and former IGS holders....which shouldn't be.
CHECK IT WITH YOUR SOLICITOR.