There is a mature clump of this a block up from where I live. I call it a "Car Wreck" plant, the kind you nearly swerve off the street or hit someone in front of you because you are so busy gaping at it. This one is in full, all day sun, a solitary plant and I yelled out "Go back Go back" to my husband who was driving so we had to circle around and check it out. It looked great as a single specimen and I cannot imagine it looking bad with what you have in mind. Let me put it this way, I wish I had a spot for one. Simply gorgeous last fall. A perfect vase, tight and red with the sun shining through the reddish seed heads. Wow! I had already ordered three of the reddish P. Rotsth........(that one with the German name I'm too lazy to look up the spelling right now)

I took the yardstick outside and measured. Mine are going on their 3rd summer from 4" pots planted in fall 2011. Height 5ft. Width at top 3ft. Exactly. They make a great specimen grass so yes, they would look very nice being the only grass in the border. I dug three 2yr old plants up last year in spring very easily but it set them back on size that year. Other comments? They look fabulous under an outdoor light, backlit by sun or in the moonlight and I love the gentle way they sway in the wind. Its one of my favorite grasses. They stay upright in winter, I almost hate to cut them back in spring. Also, they bloom for me quite early, in late June here so thats another + of a long period compared to some later blooming grasses. They will take moist soil but they have flopped down in rain when wet, they recover quickly however. Here is a photo I shot of a grouping of 3 in early July.

Interesting query & comments about the 'best' red panicum. Obviously some of this will depend on your personal view of red. A lot of the new 'red' panicums on the market have a predominantly blue-green leaf early in the season. Many of these, including introductions from my garden (Blood Brothers & Samurai) turn a deep blood red /burgandy. Many of the older 'red' panicum cultivars have a predominantly green leaf early in the season and colour up to more of a cherry red . The only one of these that I'm growing was purchased under the cultivar name 'Rehbraun' Although it colours up later than Blood Brothers or Samurai, it has a rather nice 'bushy' form that makes a stronger colour statement from a distance (colour is similar to that found on Japanese Blood Grass).

I'm in central Oklahoma smack in the middle of the Great Plains which is prairie grass country. It can get quite humid here, especially in June and we got some flooding last year--- the LBS did fine. Its sort of up to anything our weather can dish out and that involves extremes in many directions. We are famous for either too wet or too dry. Too cold or too hot. LBS only tends to flop in overly rich garden soil or too much shade. Lean soil is best. You can check around and find the best genotype for your local conditions in the form of bulk seed, I understand most of the US has it listed as a native grass. Your 45 degree angle description sounded like it would have fast run off so seems it would would be dry in summer? The best cultivar type for avoiding flopping is 'Blue Heaven' and its got great color in late summer and fall. It also seems to be more shade tolerant than all the others, surprisingly tolerant in fact. Standing Ovation is another that is supposed to be flop proof. It could get expensive buying cultivar plants if the area is big. the worst for flopping in my experience is 'The Blues' because they form such thick seed heads that they ended up being top heavy. I just replaced a stand of 'The Blues' with 'Blue Heaven'. I've had Little bluestem growing here in my prairie garden quite some time and never seen the middle die out. It grows wild around here just about everywhere and each plant is fairly narrow and tall, no middle die outs, they look more like exclamation marks. Its also long lived with very deep roots. Some types are greener, some sort of gunmetal deep blue and others are powder blue. Heights vary from one area to the next. I grow several types, both local and some cultivars but have never seen any that wasn't a great grass. Currently last years growth along the roadsides is still standing straight and tall with a definite orange color since no one trims those out there. By summer, they will be green (as long as the rain comes) and then gorgeous in fall.