Quote Originally Posted by joekinplaya
Also, it's only logical that the 4th Hokage has perfected Shiki Fuujin because the 4th described the technique to the 3rd after having to use it. Sarutobi, however, told Oro that as soon as he used that technique he had already been fated to be dead. Yet, 4th used it and was able to describe it to the 3rd... Madd confusing. So this is a theory that supports that the 4th may still be alive.
It never stated that the 4th literally described the effects of Shiki Fuujin to the 3rd. Most likely, the jutsu was developed with those conditions set as characteristic. Basically, if it doesn't exchange the user's life to seal the target's soul, it isn't Shiki Fuujin. There's no point in trying to find a loophole in that, other than not using it at all.