I can't think of any evergreen reddish/plummy-colored shrubs other than lorapetalum and nandina (which is apparently quite invasive so best to get one that doesnt produce berries). Some Azaleas have darker slightly reddish leaves, so you could look at those. If the leaf color loss is very location-specific, perhaps you should try lorapetalum there anyway and see if they stay purple there. Most Lorapetalums grow much bigger than 4' though, so you would need to keep them pruned.

Here are some other flowering evergreen full-sun shrubs, but that don't have the leaf color you are looking for (you would have more choice if you didnt mind them being non-flowering, but I compiled this list based on my searches for flowering shrubs):
Native -- Don's Dwarf wax myrtle, blueberry bushes, Lyonia lucida
Non-native -- Several different Abelia cultivars (Rose Creek, Canyon Creek, Mardi Gras), some of which have some interesting foliage, Viburnum tinus, Viburnum prague, Indian Hawthorne

Several deciduous shrubs with plummy/reddish leaves but most of these would get much taller than 4' so you would always be pruning:
Cotinus Grace or Royal Purple, Physocarpus Summer Wine, Sambucus nigra (elderberry) Black Beauty/Black Lace, Weigela Wine-n-Roses series (there are some shorter ones).

I'm no expert though, having just started planting our garden last year. Maybe you'll get some other suggestions.

Oh, Gardenia would be another evergreen choice for its wonderful fragrance, but again, not the leaf color you had wanted. The bigger ones, 4-6', as your backdrop, or the low-growing Radicans in the front of the bed.

And since your house is French-Country, lavenders would be great as fragrant and flowery and less formal. Mixed with some Rosemary and then some perennials. Daphne is very fragrant and pretty if you have a shadier spot anywhere in the bed.

The perennials forum and cottage garden forums here are nice to look at for ideas. Look at Wonbyherwit's garden, she has a lot of beds that look quite loose-french-countryish to me (and she's somewhere in the south so similar climate). She posts on Cottage Gardens a lot.

except for the height limitations, chamaecyparis thyoides 'red star' could be what you are looking for.
i hesitate to recommend it, though, based on my personal experience with it as well as reading about that from other gardeners. it is quite attractive when young and has blue-green summer foliage that turns a plum color in winter.
comments from others in colder climates indicate it can be finicky and die for no reason but it might perform better in our warmer zones if properly sited and watered. i had one for a few years but lost it. i did find it at petals from the past nursery in jemison, al. and jason's specimens in the ground were very attractive. you might research other evergreens like this with winter bronzing foliage.

one of my favorite fragrant plants for summer bloom is flowering tobacco. try the white, fragrant kind (nicotiana alata) rather than the ones with colored flowers offered during spring at the garden centers. it comes back faithfully for me every year from the roots and the scent is wonderful during the evening hours.

Here is a link that might be useful: 'red star'