Congratulations on the KR-8010. When working correctly, I have found them to be a pleasant surprise. I will not speak as to whether or not they are prone to problems or what those might typically be, as I have limited experience with them overall. From the listening sessions I have done they did the job very well, though.
As for a comparison to the KR-8050, I have not played around with one. The KR-8010 was introduced a year earlier, though - so I do not think that they were intentionally meant to be the same.
Perhaps someone more knowledgeable about the working guts could comment, I know that Kenwood made a lot of receivers in the 120-125 WPC range and I suspect that it was largely modifications on existing designs.
I will say that as compared to a KR-9050 the KR-8010 has the same spongy feeling plastic knobs, and the same plastic switches. Neither unit comes off as nice as the KR-9600 - by comparison Kenwood was moving into cheaper switches and knobs, and it is obvious in feel and appearance.
That said, I aesthetically like the knobs on the KR-8010 better than those on the KR-9050, but that is taste.
If you get yours working correctly, I suspect that you will find yourself more than happy with it.
Oh, and the KR-8050 seems to be a fair bit rarer than the KR-8010, so naturally the one commands a higher price usually.
Have fun with it and tell us what you think about it after repairs and a good listening session.