Salman,
In 2001, it could be that Piaget did not have in-house automatic chronograph movement still in production.
After the quartz era, they made ultra-thin time-date movements like 430P for themselves and other brands like Cartier. Also a few tourbillons.
So, you may be right that Upstream had quartz movements and limited editions a different movement.
The Polo FortyFive had the first new automatic fly-back chronograph movement at Piaget launched a few years ago.
Thanks for your information.
Regards,
Melvyn