I would keep the Trace until you have bought the new rig and gigged it..
I missed the tone of my old Trace amp when I bought a Markbass LM11 because I was so used to the Trace tone.
I chose the LM11 after trying (and buying) various amps, because it sounded closest to my old tone, but comparing them side by side, I preferred the Trace.
However I persevered for the sake of my back and now I love the LM11 and don't miss the Trace (or the weight) at all.
I now use the old Trace head as a PA amp and it's ideal - not bad for an amp bought new in 1984.
If you love the sound of the Trace and don't mind the weight, don't change it.