'Back to sleep' or 'tummy time'

Ah, the heated argument between putting your baby to sleep on his back or his tummy. We, of course, put him to sleep on his back when he was a newborn because he couldn't hold up his head. Although he did start holding up his head up at barely two weeks!!! However, now that he is great at rolling over, and does it all the time, its hard to keep him on his back! I'll come into his room to check on him and he's rolled over and is now on his tummy, with his hand strategically places near his mouth in case he needs a finger to suck on. I don't feel like this is a problem, really. He sleeps well, he is very healthy and he LOVES to sleep on his tummy. So, what my boy loves, he gets!!
Lately I've been reading sites about when your baby should be sleeping through the night and I realized that Ben could easily sleep through the night if I didn't get up to feed him every 4 hours. We have been trying to help get him into a routine that encourages him to sleep all night. we decided that Daddy would go in at night when he cries because if mommy goes in, all he wants to do is eat. The first night, he woke up twice and we back to sleep with a little help from Daddy. The second night he woke up once, and last night he didn't wake up at all. Usually he will wake up around the same time that daddy does, around 715-730 ish. So, I will get up and feed him then we will both go back to sleep for about another hour. I absolutely loves this because I'm getting alot of sleep. Oh, and all three mornings, Ben takes a nap around 930 as well and sleeps for another couple hours.
I'm so grateful that Toby is willing to get up at night with Ben and let me get some much needed sleep. It's been awhile since I've gotten a good night's sleep. WE LOVE YOU TOBY/DADDY!!!