Can someone explain pros and cons with Seeds?

[WwwWario]

So, I search everywhere but I can't get a concrete answer.

So I know there are achievements in the game, and apparently, you cannot earn these by using Seeds. Fair enough. But what about other unlockables? Like characters? New floors?

I'm interessted to unlock the last floor (the one with Satan) and I know I need to beat Mom's heart 11 times to unlock its alternate form, which then allows me to enter this last floor or the Cathedral. So, can I use seeds to unlock It Lives? I mean, can I use seeds and beat Mom's heart 11 times and it will work? Could someone explain exactly how this works? :)

[Biohazard063]

Under the term better safe than sorry (which sounds better than "I don't know for sure"), you're better of not using seeds. As said, achievements don't unlock and that also counts for items you find. If you are intended to unlock all achievements you're better off not using them as you can already get going on filling out your gathered items pages, get some donations in etc...

Not using seeds also means you'll already get more experience then just repeating the same run over and over. Experience you'll need when you unlock sheol. And if you get lucky (chance or forced spawn), you can get a deal with the devil/angel room to take you to sheol/cathedral even before beating It lives.

Using seeds seem to be only useful when you want to try out a certain item. Well, that and research purposes like this.

All things considered, you can try to confirm this by beating a run with a seed and seeing if your wins increase or not. Not sure if it's reliable though...