Re: Loyalty Issues
My suggestion is to talk with your Sensei about your concerns. This shows you want his input and respect him enough to be honest with him. There is no reason that I can see why you can't continue to train with your Sensei, but also learn from other Senseis . . . They can be equally good, but in different ways. Nor do I (and I would imagine, your Sensei), see this as "disloyal" . . . you simply want to expand your knowledge of Aikido.
My Sensei teaches us a great deal, but I have been to seminars, as have some of my fellow dojomates (and some of them even to seminars outside of our organization), which allows us to learn variations or things done slightly differently, and when we have questions, we can always ask our Sensei, things such as . . . "This [technique] was done differently . . . why do you prefer this way or this variation? The answers you get can get you thinking about techniques in a new way, or a new light.
Remember, ultimately, there is no technique . . . only Aikido.