Juggernaut is not immortal. The Crystal can provide him food, oxygen, water, but it does NOT prevent him from aging.
Show me one Marvel profile that says he is immortal. You will not find one. Funny thing is the Official Handbook of the Marvel Universe X-Men 2004 guide says nothing about him being immortal or invulnerable because...well, he isn't. Have it right here in my hand.
Not sure how old you are SuperNova, but you must not know much about physics. How strong is a "dimensional barrier," Nova? How strong does one have to be to "break through a dimensional barrier?" It is not SOLID, it is merely a nexus of sorts. How can you measure strength against something that is not solid? That is like saying "well Juggernaut punched through the Pacific Ocean!!!111" Whoop de doo, he punched through WATER. FLASH can VIBRATE through dimensions. Think Flash is as strong as The Hulk? Hell no. Juggernaut punching through a dimensional barrier means nothing.
If you know anything about space, you know the earth does not merely rotate, it ROLLS around the sun. Juggernaut punched through that which "supports" earth - gases, molecules, atoms. Iron Man could do it, Hulk can do it, Gladiator can do it, Superman Prime punched through TIME. Hello?
Forcefield smorcefield, it does not keep out everything. Ever heard of LIGHT? If he can SEE, light penetrates the forcefield. *sigh*
Hulk has the best healing factor in the entire Marvel Universe, Juggernaut has none whatsoever...so who beats whom?