Go for it! The key *is* heating the bottom of the board up, I have not failed a single unit. The other key is proper placement and fluxing; I spend about 10-15 minutes with a 6x loupe and tweezers getting the chips balanced on the balls from two directions. Makes for a perfect melt with 450c at 60-90 seconds 1/4-1/2 inch above on air speed 2 (really low, more like a ball of hot air than a flow)

I would also say it's better to spread the chips out than pile them on one board. The temps and power issues go up a lot between 4 and 5, and 5-6.

C