Okay, after extensive research of four modpacks and over 150 mods(if I counted right), I couldn't find any blocks that could be exploited, outside of GT of course. Now, I have to put in the caveat that not every mod is up-to-date with the absolute latest builds so things may have changed in a small number of cases.
In theory, fortune-autosmelt can be exploited. In practice, outside of something that doesn't exist in any modpack I currently play, GT is the only mod that can be exploited in this manner.
My personal conclusion is that mDiyo should put a flag that checks if a block is player-placed and disable smelting for those blocks, if he is worried about anyone abusing the exploit. Furthermore, Greg's reaction to the presence of the exploit shows that he has no faith in himself to not abuse the exploit. I can make that conclusion because he has, within the past day, said that he doesn't care what the players think. It only follows that his overreaction stems from his own inability to control his actions concerning this exploit. Here is where I could launch into a detailed psychological analysis based on his public actions, but that's not why I'm here.
My final word is that a cross-mod exploit exists. Like any other exploit it can be fixed and also abused. Also, like any other exploit in every game ever, it is not only incumbent on the designer to fix the exploit, but on the player to not abuse it as well. It is not, and never will be, acceptable for any person to punish another for using or causing an exploitable mechanic in a game. These things happen and they always will in such an amazingly complex environment as video game modding in general, much less Minecraft modding in specific. The most amazing thing about these past couple of days, for me, is the mod known for being incredibly hard, or tedious depending on which side you fall, is part of what is by far the largest duping exploit in the history of Minecraft. It is also the source of the most egregious breach of the trust we put in the modders of this game. The exploit should be fixed since the possibility remains outside of GregTech. GregTech should be dropped by anyone who is concerned with the safety of their computer because crashing the game for the decision of the mods we choose to play is a massive breach of trust.
