Totally agree - it's undervalued. But also the pieces are not cheap... particularly at retail. It's fair to say at similar prices, Vacheron and Lange probably provide more "mechanical value" in their pieces than Breguet, or at the very least, their movements are finished to a higher standard (lange in particular).
Breguet I've always thought is a bit of a mixture between Cartier and the holy trinity watch brands. Their entire production range seems to focus around only a few historical style influences - with a focus on high end case and dial finishing. Unlike Cartier however, they don't have anywhere near the general mass-appeal/prestige to the brand.
These days, many people really really value movement finishing in high end watches, and for the same price as a entry-ish level Breguet at RRP, you can easily get entry level vacheron, lange, and i think probably even some pateks, which is hard to go past. You basically really ahve to LOVE the breguet design and look I think!