I'd be curious to hear the experts weigh in, too.
I am currently doing LP with squat & deadlift one day and bench/press (and a Zone 2 cardio row) the next and enjoying it a lot. As I've progressed, I've found this impairs my deadlift on lower body session 3 of the week, so I've had to sub in a light pull day. But it's worth it to me to have the shorter workout time and more consistent schedule, because it makes me more adherant and therefore progress faster than I would otherwise. I suspect one day I'll get to a point where it doesn't work anymore and then I'll need to adjust back to "the program" or move on to intermediate programming.
I'm surprised your wife stalled so soon on LP, did she switch to 3 rep sets and 2.5lb jumps on the upper body stuff? Eat enough protein? Etc etc etc?