I've got an old and trusty Metz 44AF, sturdy as heck, good recycle time and all. It's not wireless, and it's very basic, but for the price, it's impressive.
I've heard good things about the 48 AF-1, but didn't go for it when I bought my second wireless flash, as it's, well, more expensive than the FL50R in Norway.
I must admit I see the point of going Olympus, though. You know there won't be any trouble, and if you want to sell it afterwards, I think it'll both be easier to sell, as it's a brand flash, but it'll also show up better in the lists of used gear, someone looking for a flash for Olympus might very well skip the Metz, as it's not name brand.
But if you get a good price for the Metz, and it's indeed noticeably cheaper than the FL-50R, I think you should go for it.
Just my .2