We're trying to document the performance difference of our site using different browsers. We use LoadRunner for load testing but I don't see a way to specify the "browser engine" it uses to run it's tests (perhaps it's using it's own?). In any event I'm not sure that LoadRunner is the right tool for this job but we own it so if we can use it, great.
If not, is there another tool out there that I can use to record a script and run it automatically against a site using several different browsers?
A little late to the game here, but you might be interested in checking out my company, BrowserMob, which provides Selenium-based load testing. I'm one of the original creators of Selenium Remote Control and I started BrowserMob exactly because traditional load testing tools had a very poor "browser engine" (most don't even try to simulate a browser).
If you are looking for server performance only, LoadRunner will simulate different browser engines. If you need the client side performance as well, that would require a functional testing tool.
LoadRunner > Run-Time Settings > Browser Emulation > User-Agent
Set this string to the desired string and as far as the server is concerned, this is the browser making the requests.
BTW, BrowserMob is a great option!