| Just put a set of these on my American Deluxe yesterday, and wow, love these strings. Nice tension, not too tight or loose, and nice balance between bright and mellow. I've been using either TI flats, Smith Compressors (groundwound strings), or GHS Boomers, and these Fender are awesome. They feel and sound smoother than Boomers, which can sound bit harsh and don't last much.
D'Addario XLs have always felt too rough under my fingers, sounded too bright, and had too much tension.
Also, I have a set of SIT silencers. There sound great, nice old-school sound, but they feel kinda sticky.
My suggestion then is, if you after more of a flatwound sound but don't want to go 100% with flats, go for the Smith Compressor. These are a great compromise, and these strings last a long time, very high-quality, and if you are looking for more of a smooth round sound, then try the Fenders. I 've also tried some other kind of super smooth round with round cores, which are TI jazz roundwounds, but I never liked the super low tension, and they can sound a bit thin.
Nickel roundwounds with round cores and much smoother than rounds with hex cores. I think the DR also makes rounds with round cores, Sunbeams, I think.... | 
