Reply to HD25s or Westone UM2 IEMs?

Basically I can get a set of either for about the same price. I know how good the HD25s are and have had a chance to test them out in person. Just wondering if it would be worthwhile buying the UM2s. Has anybody here had experience with them? Do you find them very comfortable? Do they have a tendency to fall out at all?

Any help would be greatly appreciated!
Cheers,
Harry