I'd say the reason Swarm will look more intimidating than Stealth is because...it's meant to!Look at Stealth's theme. Quite easily it has the most upbeat theme of any major coaster. The Swarm is meant to be imposing, intimidating, 'scary'. Stealth is meant to be big and fast, yet in a way which seems more like a challenge, something to enjoy. And, of course, the colour schemes (and I'd say even the supports) are a contributing factor to this.