Shame on GarageBand for no Tempo Changes!

Seems like yesterday I was creating my first posting to this site. Time flies when your tied to the assignments that make up the last semester of an Instructional Computer Technology degree. Anyway, over the past two months I've been preoccupied with many of the emerging technologies learned over the past two years. My teaching position requires that I produce several tracks of music, with piano accompaniment and multi-track vocals for a choral program. GarageBand has proven very useful. However, as a studied musician, I have to mention that the software absolutely fails in one key musical concept. You can't adjust tempo in a composition with GB. This truly "bites". I've found that going to my very old 386 (if you remember 1994) with Cakewalk Pro is useful. Having used that software for years, it's easy to record the accompaniment, convert the .wrk extension to .mid, and save it to 3.5 disk....email it to myself, and open it in GB. Lots of steps required to make up for something GB should have been designed to do. I know there are other products that are far better than my old version of Cakewalk Pro, but I don't have the time to check them out at this time. Don't get my wrong. Other than that, "major" problem in my composition needs, GarageBand kicks it! Any advice?