Why wouldn't you use the Spring plugin?
It's essentially invisible, uses Spring to create your actions (including injecting other Spring beans), etc.
Guice's @Inject
doesn't know anything about Spring beans, AFAIK, so you'd be naming classes manually, they'd be instantiated via normal Java/Guice mechanisms, wouldn't be injected with their own Spring dependencies (unless you did it manually, or via AOP, or whatever).
You'd also need to use non-Spring mechanisms for doing injection in testing, which is fine, but unless you provide more details regarding your usecase, I don't really see a reason to bypass the functionality the Spring plugin provides out-of-the-box.