I own an older left-hand S410 Extra, which is the FAC version of the bolt-actioned repeater, in walnut. Let no one tell you that the S series PCPs from Air Arms are less accurate than "those" other PCPs (or springer). They are equipped with match-grade Lothar Walther barrels, and Air Arms has been in the game longer than many of the current brands producing high-end PCPs. It also sponsors many shooting events and builds rifles for pro shooters. (What does this tell you?) Moreover, the S series PCPs (and springers) from Air Arms are used in a lot of field target competitions in the UK for a reason--they are precision machines that will consistently hurl pellets in accordance with their owners' skills. At least with mine, it will repeatedly fire pellets into the same hole the previous one made when I do everything right. It is that good performance-wise.
If weight is going to be a factor, and I'm thinking it might be, I think the S series rifles would not be a problem. Of course, trying to keep the rifle as light as possible will depend on the scope that you plan to pair with it. Also, you may want to consider the carbine or shorter-barreled version. Because mine is cocked via a bolt instead of the sidelever that is on the current generation, I can't speak to the sidelever's character. But in terms of performance, I don't think your wife will be disappointed.
My S410 is not regulated, but for being so it is very consistent when at its usable pressure range. The way the valving system is designed contributes heavily to its shot-to-shot consistency--and I have opened up mine numerous times to establish this. It seems to me that the valving of the unregulated rifles is designed to act as a "regulated" but not formally regulated system, if you can comprehend that. That said, though, I think the regulated one (XS) is better in that it adds even more consistent shots.
The only weaknesses in the S410/S510 guns are: (1) the small and very thin magazine cycling arm as it is prone to breaking when cycling ill-fitting pellets or when you force-cock the gun when a pellet's skirt is not flush with the magazine's face and (2) the location of the safety button being on the trigger (this can be dangerous for imprudent owners). I think Air Arms has replaced, however, the cycling arm with a more robust one as I see Pyramyd Air (an authorized dealer of Air Arms) now sells it, but this would be a very good question to ask the folks at Air Arms to confirm.
Fit and finish are excellent. In addition to the S410, I own a left-hand TX200 MKIII in walnut, and I can say that the build quality of both is right up there with the best. There are no plastic parts, with the exception of the external parts of the S410's magazine, to cheapen the quality of the rifles. At any rate, I think any Air Arms rifle your wife decides to own will serve her well for a very long time provided she maintains it regularly.
Good luck!