few questions

well sounds good, i have heard other places too that its a myth. and thats good to know that the rodent wont do very much damage if any at all

would a 20g rat pup be too big for Mars? hes about 105g last time i checked he may be a bit bigger now seeing that last time i checked was two feedings ago

It's a little big. You can try and see if he'll eat it. The general rule is 10-15%. Usually they won't eat it if it's too big. Basically it becomes a race. You want your bp to be able to digest his meal before it spoils. If it is taking him too long, he's not getting the nutrients he needs. But, I really don't think a 20 gram'r would hurt.

I also feed all of mine in their enclosures. I've only been bit once, and it was a hatchling who thinks she needs to eat everything that comes in her cage. Rats/mice have a different heat scent than we do, and they smell way worse (well, that is if you wash your hands regularly). Remember, they can tell the difference between you and a rat, if you handle him on a regular basis (except when he's digesting) and make sure to wash your hands.

Just remember to watch them. If he doesn't want it, take it out. I only give mine about 10 min. I can usually tell if they are interested or not. I once had a rat start licking my bp all over, and then just curled up and went to sleep snuggling next to her. My bp looked at me like, "what is this? I'm not going to eat something that licks me." Lol.

Good luck!

maybe i should just wait a little till hes around 180-200 grams to switch to rats?

Depends on the size of the rats.