I have a 405...I do like it but do know that there are definitely some flaws to it...which is why the are back to the 300 series stuff I think. I like the size of my 405, but true, you have to "tap" a lot of steps to change thing and sometimes I can't seem to get back to where I want to do. But I can't imiagine not running without knowing my TRUE distance now. I dont' really have to plan a new route, I run and add on as needed.
I like the GPS part and not worrying about a foot pod and how accurte it is.
405 is nice d/t the size--more like a large watch (still big but do-able). But since I really haven't looking into the 305 I can't comment much--other than I think having a GPS "watch" is worth the $$ investment. IMO

Happy shopping or at least have fun putting it on your "Santa I have been a good girl" list.