My opinion is coloured by never having seen Metroplex in the flesh, but I think Fort Max is amazing. There's a huge amount of fun to be had just with Cerebros and Emmissary. Even at dreadful Myer prices this is a purchase I feel was worthwhile.
Or one could wait a few weeks and buy it from Big W for $160 odd less. I wonder why they called the smallest Headmaster unit "Emissary" instead of Spike, because we know that Hasbro still holds the trademark for "Spike Witwicky" from Dark of the Moon.