I have a ten year old a6000 in good working condition and am thinking of updating to the a6700. Are there advantages of the a6700 over the a6000 that make it worthwhile (apart from the a6000 being ten years old)?
Yes its a very good upgrade. "Worth" it depends on how much YOU value the difference.
I upped from an a6000 to an a6600 and find the expense to be worth it. Mainly I value the silent mode, IBIS, and the bigger battery. Already having my a6600 Im not much tempted by the a6700. If I were still using an a6000 then I know I would today be choosing between the 6600 and 6700 as my upgrade.
OTOH, if all my lenses were OIS and silence were of no value to me, that leaves ONLY the bigger battery to tempt me, and I would NOT have abandoned my old a6000 for just that one single improvement.
I suggest you compare the 6600 and 6700 as both are available, and decide how far you need to jump up at whatever the cost difference is. My 6600 was absurdly cheap as an open box special ($700) so for me the 6700 was not even in the running. At "normal" prices, maybe I wouldve spent the extra for the 6700 !
I find online talk of "familiarity" and the "learning curve" meaningless for me. I can use any camera like its an old friend. But those things matter to some users and so Ill point out that the 6600 is operationally the same as your current 6000 while the 6700 has a different interface. Its up to you whether that matters.