"What is the Orthodox reading of 1 Cor 3:9f?"
Do you mean 3:9? If so, it means we work synergisticly with God. We participate obediently in His work.
8 ...And every man shall receive his own reward, according to his own labour. 9 For we are God's coadjutors: you are God's husbandry; you are God's building. 10 According to the grace of God that is given to me, as a wise architect, I have laid the foundation; and another buildeth thereon. But let every man take heed how he buildeth thereupon. 11 For other foundation no man can lay, but that which is laid; which is Christ Jesus. 12 Now if any man build upon this foundation, gold, silver, precious stones, wood, hay, stubble: 13 Every man's work shall be manifest; for the day of the Lord shall declare it, because it shall be revealed in fire; and the fire shall try every man's work, of what sort it is. 14 If any man's work abide, which he hath built thereupon, he shall receive a reward. 15 If any man's work burn, he shall suffer loss; but he himself shall be saved, yet so as by fire.(1 Cor 3:8-15)
Yes, I should have included v.8. The mentioning of "reward according to labor", it seems to me, places the judgement at the time of judgement after death, hence the connection to purgatory. Also note the "day of the Lord". The Orthodox read it as santification during the lifetime? All of them?