for $850 after the repair and upgrade, you cannot beat that amp for the price. Unless you are seriously considering spending quite a bit more money for another amp, I would keep that amp and upgrade/repair it for that costs.
Again, if you have the money, then by all means, consider another amp. If you are staying in the used category and still want solid state, then for around the $2000 category, recapped mark Levinson ML3 (yes I recently sold one), classe 201 and 301 amps are very nice, and there are many others, including Threshold, Bedini to name a few.
These are relatively easy to work on by a good technician.
Don't stress over this. Even if you repair/upgrade the amp and decide later you want to sell it, you won't have much trouble selling it for a good price.
So, do what's comfortable for you and enjoy.