I got both my leaders from RK with no problems. You could get both of them for around $80AU each, not a bad deal i think (i mean Movie Leaders are more expensive than that on sale now at BigW ... although there was a time when they were much cheaper too)
I think they upgrade to EMS (at no charge/mention) for large boxes, even if you choose regular shipping. I've been upgraded when i ordered:
1) L.Megatron and V.Starscream
2) L.Bulkhead + BT20
So i'd imagine buying 2 leaders would get upgraded too! Even if they didn't upgrade i think it's worth it if you want the toys early or don't want to hunt around come local sale time.