Welcome aboard the Taperssection ship of fools!
[snip..]sound effects editor for TV and film.
[..snip..] I am starting to build up my own simple rig, mainly for adding to my sound library.
I too think the Shure a better fit for your stated primary use of populating your sound library.
If you need to keep your costs low and were are only taping concerts from the audience, the ART would likely be fine. It is not nearly as solidly constructed as the Shure, and as a phantom-only supply it will power the microphones, but that's all it does. It will work fine for louder material where not much gain is needed and for things where its good analog limiters and high-pass filtering are not needed.
For recording low level sounds cleanly without noise the FP24 preamp will be superior in that it provides lots of gain with a low noise floor, particularly needed if you ever use dynamic mics. It's professional grade equipment that is built like a tank and provides other functions which are likely to be useful for your stated use, primarily it's high-quality analog limiter circuit and switchable high-pass filters, which helps accommodate highly dynamic sounds (bangs, crashes, sirens, gunshots, trains..) and windy outdoor conditions. If you monitor using headphones while recording, it is also very well setup for doing that. In addition, it represents "accepted kit" in the professional sound world, and is a buy once, use forever type of thing.
Personally I'd go with the Shure.. or look at new recorders (other than your Tascam DR100mk2) that provide phantom, sufficent clean gain, and the features and user-interaction you desire. Give that second option some thought if compactness of the rig and simplicity of setup (mics>mic-cables>recorder) is particularly important.