Keep Or Sell - 1980 China 1 Yuan Piedfort Proofs

Recently bought a group of Chinese 1980 proof coins. I paid what I thought was quite a high price for them, with the intention of getting them slabbed and perhaps keeping a few years - the prices have gone up quite a bit recently.

Then when I looked closer I realized three of them are piedforts - confirmed when I looked at the old sales invoice from 1981 that came with them. the Piedforts are currently fetching about $1300 a piece before commission at auction, and the mintage is very low - 2,500 according to krause.

So really just wondering if anyone has an opinion of the Chinese coin market - many of the more common types in high grades seem to have plateaued in price the last 6 months. But is it perhaps worth holding on to the lower mintage pieces?