Kudos to your sensei for not pressuring you, and for letting you make your own decisions.
With that said, I think you should stay where you are and keep training until you see that your speed and agility is an asset to your karate.
Hopefully you'll see that as you continue to progress that the basics that you have will build into things that will benefit you the rest of your life.
If you insist on playing with the flash, why not keep training in Shorin Ryu and supplement it with the flashy stuff you desire? My guess is that if you do, you'll see that sticking with Shorin Ryu is wise. If you don't I suspect you'll either return or get totally disconnected.
So my recommendation would be to keep talking to your sensei. See what he thinks about you keep training and adding another art. See who he recommends, and how he would incorporate it into your current training.
BTW, you said you've been training for several years. Have you earned your black belt yet? If not, my advice was written not thinking and figuring that you have. If not, stick around and earn your black belt as you have a lot invested. Then train to complement what you've learned after you see what else you need. If you don't already know, once you get to black belt your training will be totally different and you'll be working on making your art "your own". So that would be the time to experiment a bit and to add the flash. Until then, you're still learning the basics as others have said.
You want to leave to learn some flashy stuff so you can look cool and show off? That is disappointing! Your whole reasoning is disappointing and shows little understanding of martial arts and a whole lot of immaturity (not trying to be mean). You should really think this through. How much have you learned in Karate and how much more is there to learn? I have been in Shorin Ryu for 20+ years and have not even scratched the surface. I still train regularly and learn more and the advanced stuff is way cooler than any beginner stuff in any style. All you have is beginner stuff to which you want to add more beginner stuff from other styles. It may be different beginner stuff but it is still beginner stuff so all you will end up with is a whole lot of beginner stuff and never get to the more advanced techniques, the really cool stuff. So really think this through. I could understand you leaving if the teacher was mean or not good, the school a Mcdojo or you didn't learn anything but leaving to learn flashier stuff..... and what makes you think that Karate moves are slow? If you are really that fast learn fast Karate techniques. If you can't do that then you may not be as fast as you think.
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Two comments for you:
1) You are in college and have trained in your style for 7 years. That means that you were about 13 give or take when you began your training. That alone tells me that you do not yet understand your style nor have you developed a high level of skill. Leaving now means you will have missed the best part of your training.
2) Your profile is a violation of Yahoo Answers Terms of Service and has been reported. This is not an advertising forum. If it were, I along with many others would use it for advertising.
Just because you might want to take up something else does not mean that you have to completely leave or forgo Shorin-ryu. I think you are looking at this in a somewhat limited way and maybe you should consider expanding your thinking and approach here.
You're doing the right thing by leaving. No point in staying where you are when you want to be somewhere else.
I've studied shorin ryu for a number of years now, and I enjoy it, really do, but I told my sensei that I think I wanna move on to an art that fits my desires, I'm very fast with my hands and am a good at close distance so I figured I'd learn wing chun, and I'm very quick on my feet and at doing trick kicks etc so I thought of also combining WC with ITF TKD, I personally don't like WTF TKD even though that's the one with flashy moves, anyways, my sensei said It's a little disappointing that I wanna leave the school, yet he understands, but the end of this would be, is it right for me to leave and do something else?
