If you have the chance to try them side-by-side, I think you might find them to be very different skis.
I ended up on a demo pair of Explosivs last season (Maroon red with the Bhudda sticker on them). I was trying to demo Stockli's but due to a mix-up over the phone when I got to the shop they didn't carry Stockli's for demo. They gave me a set of Explosivs with the following advice: "just point 'em down the hill and rip." We were riding Sugarbowl in Tahoe a day or two after a mild storm, so there were a few powder stashes, but most of it was tracked out. The skis handled great in the pow, but once i came flying out onto the hardpack groomers I was all over the place. Needless to say, they worked me around quite a bit. I found them to be incredibly straight and unweildy on the groomers. I actually ended up taking them back to the shop and exchanging them for some M:EXs, which were much better for the conditions.
A few weeks later I demoed a pair of the Mantras and found them much more to my liking. The added sidecut makes them much more nimble in my opinion, as well as a bit more versatile in an "all-mountain" setting. They hold up nice in the pow, but also get by in the groomers, as long as it's not icy.
As for the "Cult" status of these skis? I think you'll find that the Explosiv has much more of a cult following with hard charging skiers and that the Mantra is, at least in my opinion, a much more mass/average skier oriented version. That's just my take, though.
BTW, I'm 5'11", 185lbs somewhere between a level 6-8 skier and while I tend to gravitate more toward off-piste, i would not consider myself a hell-bent-for-leather hard charger. I'm a little more reserved. Which is why I think the Mantra fit me better than the Explosiv.