I'm going with all Carbon Fiber on my Revo, but I wont know about strength and durability for racing until I've run it some. The integy is cheap for a reason. If you're going to go with alloy, I highly suggest a company that has a warranty and customer service, such as Golden Horizon or East End Machining. I refuse to buy anything from integy. The main problem that I have with them is the way that they treat their customers. If you buy something from them and it breaks or you need assistance, you can NOT call and talk to someone about it. You have to go through this whole "ticket process" which can take weeks on end, and even after that it's hard to get anyone qualified on the phone that speaks good English. I like to buy from companies that stand behind their products. If you have something from Golden Horizon, and you crash and break an a-arm for example, you send it to them and they send you a brand new one, no questions asked. It's also much better quality. However, there are some parts that you don't want to use alloy if you're going to be racing. For one thing, the aluminum is going to be heavy, and if you bling your ride up, you're going to have a serious disadvantage on the track. That's one reason that I'm going with all carbon fiber on my Revo. Second, aluminum bends and it's no good anymore. If you bend it back, you will only weaken it more. If you go with some RPM arms and body mounts, things that take the abuse, the parts will giev in a crash and spring back in place on impact, thus acting as a shock absorber and staying in perfect condition with no weakening to speak of. If you can manage to break one, they will replace it no questions asked.
I say stay away from integy first of all, and if you will be racing, watch the weight and use RPM arms if possible. Aluminum is pretty and I use it on my shelf queens, but if it will EVER see fuel or a battery, its only RPM arms, or a similar brand plastic or nylon, like Tekno RC. I am looking for some carbon fiber arms though.