I am a big fan of Roush but they have some quirks like requiring an ASE certified mechanic to install, change
oil every three months and they want it done at a "service station" with receipt to maintain the warranty. Now I would suspect if an issue arised and you did not comply they would cover unless you just did something stupid but the wording is in their contract you agree to when you purchase.
Being a "do it yourselfer" I would prefer to do my own install etc, but I would buy a complete running engine that has been dynoed before I receive. It is because of that Keith Craft is hard to compete with and has a little better pricing. So if you are going to have someone do the install use Roush or KC, do your own install I would have to lean toward KC because he does not have some of the stipulations Roush has in his warranty.