Re: DLS RS5A V.S. Boston Acoustics SE50 Components
They're both good brands known for good sounding speakers. To the durability, barring abuse they will last much longer than it takes for most people to get the urge to try something different. Boston Acoustics has pulled out of the car audio market, but they're continuing warranty support.
I would try the tweeters in the stock location first. If you don't like the sound you can try some temporary locations with velcro to hold the tweeters in place. Some people like the sound of tweeters on the A-pillars, but it will introduce issues with reflections off the glass. You can also consider putting the tweeters in spheres. There are a couple of threads on the site discussing how to do this.
New online business launching soon. Specializing in car audio system designs and sales for those seeking great sound.