I second that idea, big time. When I first got the FH5's, I was convinced that none of the included tips worked for me. Couldn't get a decent seal at all, and they came loose in my ears after a few minutes. I then tried spinfit 155's and 240's (with good results) and various other generic double flange tips before reading the post about pulling one's ear back while inserting.
Then I went back to the FiiO large bass tips and found that when properly inserted they work great for me; not exactly the same as the spinfits as each tip has a slightly different sound signature, but I really liked how the FiiO bass tips sounded when properly inserted, and I preferred them to the spinfits. It was a complete revelation and made me feel foolish for having spent so much time trying other tips.
Having said that, I had already ordered Spiral Dots, model EP-FX9L-B, and think they beat everything else I've tried for both comfort and sound quality, so I've settled on them for now. Bought them on Ebay from a Japanese seller, and in spite of warnings about Japanese customs delays, they showed up here in California very quickly. They feel like they don't go as deep in the ear, but they provide an excellent, comfortable shallow-insertion seal. They bring some nice bass, too, which I like. I can HIGHLY recommend the Spiral Dots.
I'm still waiting for the Symbio's that I ordered nearly 3 weeks ago. I'm hungry to try them, but apparently Hungary is not in a hurry to get them across to the States. I will report on them if and when they show up, but in the meantime I'm completely satisfied with the Spiral Dots and the FiiO bass tips, when properly inserted.
Of course, Your Earage May Vary.