Just watch out for falling portals

I'd agree with Harold here.

IIRC in the first Portal game the portal is reset if it's support moves. Where's the moving one in P2 already ?

I saw a portal video on youtube where some guy showed that moving portals didn't affect your distance/speed, I couldn't tell if the portal was moving, and if it was, it probably wasn't fast enough to make a difference.

Keep in mind physics works the same no matter what perspective you use. This means that a portal falling towards a box must have the same result as the box falling toward the portal, but you have to take into account the difference in velocities of the other portal when changing these values.

The proof for that lies not in the classical physics, but in the calculation of gravity fields. As a gravity field goes through a portal, it would still have to function, since objects that have gravity fields still function. As such, the gravity fields between the two portals would distort and, to a certan extent, balance, meaning no using portals for accelerated wall hops.