I tried the instant release addys back in college and enjoyed the effect, but I used to get headaches from them as well. That was 20 years ago.
I've been taking Modafinil (generic for Provigil) for about 2 years now and love them. I don't take them on the weekends, unless I need to get a bunch of shit done and need the extra boost, but they work great for me during the work week. I've tried the newer version, Nuvigil. It gives you a speedier feeling and doesn't last quite as long IMO, so I've stuck with the less expensive generic, Modafinil and its worked great.
I started out taking a half of a 200mg pill for the first 6 months or so and that's all I needed. I eventually started taking the whole pill, first thing the morning and it works great all day. I can still take a half and feel the effects, but 1 is the perfect dosage. 1 1/2 if I really need an extra boost or didn't sleep well the night before.
Getting your Insurance co to cover them will be the biggest hurdle. I actually had a sleep study done and was able to use "restless leg syndrome & slight sleep apnea" as my reason for needing them. My wife also got a script for them after she tried a half one of mine one day. It was much more difficult to get Insurance to cover hers. Fortunately we have an awesome primary care Dr that wouldn't give up. After the third try and using ADD as her diagnosed need for this medication, insurance finally covered them.
I can't say enough good things about this drug. No bad side effects, no crash, you can stop them cold turkey without a problem. (Aside from being a little more tired than usual for a couple days after you stop taking them, but nothing a couple cups of coffee won't cure) The focus & energy it gives you comes on slow but noticeable and there are no jitters, sweaty face or palms, just an amazing focus and energy much different than Adderall. Even after being on them for two years, I still do quite fine with a single 200mg pill for the day. While everyone is different and size likely comes into play with dosage, I've never taken more than two at a time. I simply haven't needed to.
If you can get your Dr to prescribe them and your Insurance co to cover them, I highly recommend Modafinil.