When I was young and foolish, after trying out many many different boots, I went for the stiffest boots I could find. My primary motivation was to get the maximum performance, most instant and precise response. I wasn't a racer, but I was deadly serious about going as fast as I could possibly go. I found I could also ski these at normal speeds, and did indeed use them in all types of terrain free skiing. However my form was severely hampered. I think there's a little cartoon vid of someone skiing without moving his ankles somewhere. It's not easy absorbing moguls using mostly the waist; it produces some interesting fore-aft balance challenges. Those boots (Koflach Comp 911s for those that know) had plenty of bells and whistles for all kinds of adjustments, but because the custom foamed liners were tripple-stacked to concrete-like hardness, the boots were basically cast in stone. Though I had to adjust, they were still preferable to most boots I could rent.
More recently, after settling down in my old age, i figured I wouldn't be risking my life if it took an extra .03 seconds to initiate a turn, and went for a much softer pair of Salomon Cross-max 10s (now X-wave). I told the guy at the shop that I wanted one-step short of a racing boot. While I was getting them dialed in with several trips back to the boot-fitter for stretching, I had to rent mushy rentals. In the end it was worth it;not only do my feet not hurt after 1/2 an hour, the suspension-payback in the rougher terrain and softer snow is amazing.
After exploring two extreems, I think that a boot just shy of what would be ideal for racing would be the best choice. I don't think my Cross-max's, though certainly a little easier-going, would prevent me from being competitive, except at higher level racing. Note: I'm talking top end of the recreational scale, not mid-range.
I think that unless I had a LOT of time to practice, having two boots would cause me more trouble than it's worth. I tend to grow into my boot. It takes me a long time to get used to something, but when I do it's like it's a part of me.
In summary, get a single pair of boots on the stiff side, but not quite as stiff as you would want for full-on race-only boots. Most importantly, get them properly fitted!