hmm... well as far as the panels matching each other it should be fine as long as your gauge remains consistent and you aren't using different yarn for each panel. At least that's what i THINK... maybe i am not thinking right though.
however it would probably change your finished product size since encore is a lighter weight gauge. just not sure how much it would change it.
the elann stuff would match pretty close but yes you would need more skeins than the pattern calls for since it is something like 30 yards shorter.