depending on WHEN the gun was imported into canada, it could have fallen under the old 407+fps rule or the new 366+ fps rule.
A teammate just recently purchased a KAm4a1 and it shot 420 out of the box, so this meant it was an old one imported last year or early spring. Depending the stock of parts on hand at the manufacturer as well, they may not have run out of 400+fps springs until long after the rule changed, so guns coming in may still have been shooting higher than 400.
Best bet is when you buy the gun, have it chronoed at the store to find out if you need a spring swap or not.
I would take the KA over the WE.