I'll use any tool, anytime, anywhere.
I started using the transpose just to give my voice a break, but some songs are so much easier to play in certain keys that it becomes a neccessity to get the proper voicings. eg: certain blues riffs that require pull offs or quick grace notes. Somethings work better if you move a 1/2 step up or down. I do most of my blugrassy things in F, even if I sing in E so I can use my blues pickin' styles. They just don't work in E!
If I forced to use an acoustic instrument .... then I live with it, but the end product is better with the proper tool.