Yeah if you need both those sounds, I could understand both.
I'm not a stealth fan at all, and I'm especially not a fan of modern heavy tones, but it seems to be one of the most loved amps for that style. Channel 3 is a mess IMO, but channel two and channel two with a boost is a very clean, very anodyne, very modern rhythm tone. That you could totally use for meshuggah, periphery, Black veil brides, and whatever the 14 year old goth chicks are listening to.
The SLO however is TOTALLY my speed. It's bloated, creamy midrange is one of the best amplifiers I've ever used for recording leads. You can get surprisingly good semi modern rhythm sound with the crunch channel and a tube screamer, as well, in my opinion. But when I say semi modern I mean late 80s early 90s thrash. But where it really shines is the lead tones, the clean tones, and the sheer midrange balls.
They really truly don't have a lot of overlap, so if OP already has a SLO, if you want that modern tone, the stealth really isn't going to overlap much.