Playtest cards in non-sanctioned events = OK
Playtest cards in sanctioned events = not OK
Let's not make this bigger than it is...
Unfortunately this is incorrect outside of the US and has been for some times. Nothing is put in writing and stores won’t say anything directly; but in a choice between keeping their WPN status or running non-sanctioned events with playtest cards..... the event don’t run. It’s a stark choice.
@portland Heaven forbid we had a central location to discuss the merits of each rule set and reach some sort of conclusion !
Played CFB rules at the GP last weekend. Mana burn was interesting, Hymm added precisely nothing to the quality of games, pump knights don't seams necessary or vastly better (they squeeze zoo out a little), and multiple workshops are as good in a relatively weak format as you'd expect.
I still like the Swedish rule set with greater set legality. But, each to their own.
AK was always reasonable, although has been surpassed. Impulse is never great, but a semi-reliable T1 play, although not half as good as Jace-V on T1 if you get to untap. Opal and Top heavy builds get Thirst. None however are mana-free, but I guess that's the point of restricting the free-draw.