My stats are already above the 2300 stat cap for weight, which proves that pets can gain dex even when they are capped.
700 * 3 = 2100
384 * 0.5 = 192
92 * 0.1 = 9.2
-------------------
+ = 2301.2
I maxed out my stat weights before going to fight more things for dex gains. I'll never be able to take dex to 150 with this particular setup, but it does show that dex will continue to gain until the soft cap of 125. If I really have to, i'll take that mare and go train it to 125 to finish the proof.