I actually found your post via a Google search, as I was trying to find out if anyone was looking for these! My buddies and I just placed a huge order to Forgeworld and I accidentally bought too many of these (didn't read the fine print, there are 3 to a pack... I bought 3 packs... d'oh).
They weren't as big as I thought they would be. They're about 3" - 3.5" tall (with a pronounced lean of about an inch) and they look reeeally cool.
They're INCREDIBLE tank poppers and power armour disintegrators (don't think I'm allowed to post their exact stats on here, am I?). The only drawback is their odd rule about when they explode. Each spore releases 1D6 - 1 deadly bio-acid spores. The bio acid spores are WAY better than the basic spore mines in the new codex, but the 1D6-1 thing means you may not get as many as you'd hope.
I might be interested in selling off a pack of 3, as I doubt I'll ever field all 3 units of them. Are you still interested?