I think the fact that Stealth has height and Rita doesn't will make them appear two different coasters to people. It's the theme that probably lets them down.
People won't compare. They'll see two completely different coasters. Stealth has height, a very impressive looking top-hat feature, Rita doesn't. They both launch, so what, as Williscroft said, there are dozens of ride types that feature heavily throughout the UK and the world. They're going to look totally different coasters.
Although in my mind, Stealth will be enjoyable...but change the way we look at coasters? Not the enthusiasts, certainly, the media might cover it extensively, but it's not going to exactly be the best of the launches, is it? Coaster technology has progressed so much during the last decade, the coasters that came out in 1994 (mainly Nemesis, the Big One and Shockwave) all had that something that appealed to the public that had never been seen in the UK. Stealth doesn't really have that, in terms of height or speed, or even visual impact.
It looks like it's going to be great, don't get me wrong, and it's great something like this is coming to the UK. But perhaps we should steer away from the comparisons.
I've come to think it's such a shame that new coasters are dogged down in the planning/construction/opening stages by comparisons to another coaster - not judged on its own merits. Sure, compare to Rita, KK, TTD, Xcellerator to help form an argument, but don't BASE it on the comparisons. They're going to offer different ride experiences and they're in different locations.