Rademaker,
Rapogee's experience leads him to the conclusions he's made. However, my own experience markedly differs from his. That's OK - life would certainly be boring if we all shared the sames tastes.
For a different point of reference, my original intent was to actually buy the SF. However, after comparing the two for almost 3 hours straight, my ears told me otherwise and they sent a memo to my wallet accordingly. This despite the ACs being more that the SF and the fact that, e-ghads!, they're made in (Audiophile God forbid it) China as well!
Everyone has there own individual tastes and perception of quality and/or sound and the proof of the pudding is in the tasting. Assuming that parts quality, design, and execution are commensurate, declaring that one brand is better or will put another to shame is strictly an opinion and not fact.
For a further point of reference, the other monitors I own, including Focus Audio FS-688, Micropure Kotaro, Zu Tone, and AAD PPM1, in my opinion, easily offer equal or better, depending on taste, any of the lesser SF lines. In particular, the FAs and Kotaros have been universally praised and are considered by many to be right up there among the finest of monitors both sound and buildwise available today regardless of price.
Now, I will grant you that Guarani is diffent story - this is a very fine speaker soundwise and I actually prefer it to its bigger brother the Stradavari. In addition, it exhibits uperb fit and finish and its not hard to see why people are willing pay a very steep premium for it. That said, I would put up the fit & finish of the Focus Audio FS-688, Micropure Kotaros, and, yes, even the AC V3M right up there with any of the other monitors in the SF line.
In the end, if you can, try to hear both and pick the one that your ears deem best. A big part of the fun of this hobby is in the hunt - especially with so many fine products available.
On that note, Good Hunting!
Cheers,
Garry