A capo can also change the voicing of the guitar. For example, have one guitar play in C in standard position at the nut. Have a second guitar play with a capo at 3rd fret and play in A.
The capo transposes the second guitar to C but the voicing is different and can blend really nicely.
This is why I use the capo. I can transpose in my head, and it just makes sense. Why would I play a song in Eb when I can simply capo on 1 and play with a D shape and get the sound I want? I usually plan around the capo though so that I don't have to take it off/on back and forth. It is an outstanding tool, when used correctly!!
I can think of no situation that you would want to use a power chord unless you are playing electric. I play predominately open chords on acoustic with our praise band. We use both a lead and rhythm guitar, bass, keyboard and drums. The open chords provide a better fill to the overall sound. If we use 2 acoustics then we will always have one playing barre chords to provide the additional voicings.
Power chords on acoustic can help give a driving rhythm. Sometimes it isn't even a chord but an interval - just playing 2 notes. for example play a G5 and pick a rhythmic G D G D G on 1st and 2nd strings. We are playing Hosanna by Paul Baloche and Brenton Brown on sunday and that is my opening guitar part.
That's true, it isn't for acoustic guitar... It's for acoustic rythm guitar. One is more laid back and has just acoustic-like strumming while acoustic rythm guitar is using your guitar like a percussian instrumnet (while still getting a chord out of it).
I won't often use a power chord on my acoustic. I have a elec Bass, my (leader) AC guitar, and one or two other guitars, both electric. So separation (giving sonic space) is a challenge for the team. Usually I direct
1. I use lots of open chords on the AC Guitar
2. Rhythm eGuitar uses power chords with distortion
3. Lead (eGuitar #2) uses specific sound effects to differentiate from rhythm eGuitar.
Listen to the 'Top 5 guitar chords' video for ideas on open chords...
Years ago I had the opportunity to listen to Paul Baloche during one of his stops at the Breakforth Conference in Edmonton, Alberta. It's where he displayed a great way of playing more open string's when playing in the key of E. I've forgotten what he actually called it, so now the gtr. players on our team usually just refer to it as the Paul Baloche system:-)...Instead of playing the E major chord in the 1st postition (within the 1st 3 frets),... play the E chord as: E (6th string) - open || A (5th string) - fretted at the 7th fret with 1st finger || D (4th string) - fretted at the 9th with the 3rd finger || G (3rd string) - fretted at the 9th fret with the pinky || B (2nd string) - open || E (1st string) - open.............................using this same fingering postion (using your 1st finger on your left hand as the "indicator" finger).............play this position at the 2nd fret and you have your new B chord.............play this postion at the 4th fret and you have your new (relative minor) C# minor chord........play your A chord with the bottom two strings (strings "B" & ""E") and you have your "A" chord...........these are the best chords to play "Open the Eyes of my Heart" with.....and if you experiment........there's hundreds of songs that you can use this chord configuration with, when your in the key of E.