Well, I don't know why the RAM upgrade is discussed in GPL v1.8.1.7 thread...
So just a short comment...
You don't need any special desoldering station - just a hot-air gun can do the job - of course you must cover other components a bit.
There should not be a problem to double RAM memory as the chips have exactly the same pinouts including address lines:
Original chips (4Mx16):
http://www.amictechnology.com/pdf/A43L2616.pdf
Alternative chips (8Mx16):
http://www.amictechnology.com/pdf/A43L3616.pdf
This rule should be valid for other chip manufacturers as well.
Who will be the first tester?