My 1206 is the same vintage and it sounds great! If you can listen to it and be sure that it sounds good, a faulty filter cap should certainly lead to degraded sound.
It's your decision. Save the $ today and accept the risk of cap replacement in the future, or spend the $ now and not have to worry about it for another 20 years.
When I bought my 1206, I chose to save the $ because I can do cap replacement myself when the time comes.
One word or caution to anyone replacing filter caps on the 1206---
It does not have bleeder resistors on the filter caps! That means those large caps can stay charged for a really long time after power is disconnected. It's only a concern for the tech doing the work, he must manually bleed off the charged caps before working on it.
This link is pretty good to show what is involved with cap replacement
http://www.norbern.com/parasound1.htm
They want $350 for parts and labor, + tax and shipping
Do you NEED 6 channels? If 5 will suffice, then I would be taking a good long look at this Outlaw for $600!!!
http://www.outlawaudio.com/products/5000.html
http://www.audioholics.com/amplifier-reviews/outlaw-5000