HR types (and others) - employee move from grade 15-0 to 14-10?

I have an opportunity to take another job within the gooberment, it’s a grade MS14-10 (MS = management supervisory) and I’m currently a CS15-0 (CS = career service). So this would mean taking a voluntary step-down of an entire grade, but stepping up from CS to MS. In terms of actual money it means a $20K raise, so that is my main motivation.

I’m wondering if anyone things that taking a grade step down could be seen as desperate (I must need a job badly if willing to take a lower grade) or otherwise result in any kind of a skid mark on my career track.