Thanks wzzy22!

After posting I finally found this:

xi. Changes to bookings towards which WestJet dollars were applied on a Member Exclusive Fare are permitted, subject to WestJet’s standard change policy and standard change fees will apply. See westjet.com/fees for details. For changes on a Member Exclusive Fare, the original booking will be cancelled and a new booking made, subject to availability of an equivalent Member Exclusive Fare. If an equivalent fare is not available, the booking will be cancelled and the WestJet dollars redeemed towards that booking will be reinstated to your account. The original expiration date associated with those WestJet dollars will continue to apply.


xii. Cancellations to bookings toward which WestJet dollars were applied on a WestJet Eligible Fare or a Member Exclusive Fare are permitted, as per WestJet's standard cancel policy and standard cancellation fees will apply. See westjet.com/fees for details. The WestJet dollars amount redeemed towards that booking will be reinstated to your account. The original expiration date associated with those WestJet dollars will continue to apply.

www.westjet.com/en-ca/rewards/terms-conditions


... and under the fees page (http://www.westjet.com/en-ca/travel-...s/service-fees) I found:

• Refer to Econo attributes for Member Exclusive fares

So it does look like it is most similar to an Econo fare, but with no rewards points and a little less flexibility in terms of flight changes (needs to be a member exclusive fare), but it does look to me like date changes are permitted (but I guess it's really same as cancelling/re-booking).