There are no known conflicts with the PCMCIA port at all in using this card in the A1200.
If you are not installing into a tower'ised setup, please ensure your power supply is not one of the lightweight ones - use one of the older heavier A500 types for system stability.
Ignore the physical weight of the supply - it is irrelevant. The one I use delivers 4.5A of 5V and was made in India, it is a "light" supply. Besides, what has this to do with the question?