I shudder when I find errant MegaBloks in my LEGO elements, but admit to admiring certain in-the-box models offered by them. I know the pictures depicted on the MB boxes are not actually photos of a completed MB model. They are computer enhanced images of what an ideal model would look like if MB pieces actually fit together correctly. Is there a link with images of any 100% LEGO element models built using MB instructions? If there isn't a link, can someone please post an example?
It really depends on what you mean by "accurate." Most (probably 90% or more) of Mega Bloks elements have identical, or at least functionally identical, LEGO elements. However, there are a number of Mega Bloks elements that you can only approximate with LEGO elements. For example, Mega Bloks hinges rotate around the center of mass through 100+ degrees center at the vertical, whereas LEGO hinges rotate through 90 degrees from horizontal to vertical. Also, Mega Bloks has a SNOT piece with studs on both sides that LEGO unfortunately does not have.
If you are willing to slightly modify the instructions and accept a slightly different model, then yeah, you can reproduce anything made by Mega Bloks using LEGO elements. But if you want the models to be 100% accurate, then no, not all Mega Bloks sets can thusly be reproduced.
Yes - I remember as a child, I built the USS Kittyhawk (a set that is an absolute nightmare to build with Mega Bloks) out of LEGO parts. All of the pieces, aside from the stickers, have either an exact or pretty close LEGO equivalent. You will also need to do the deck with plates instead of the large MegaBlok plates, but this allows for much more detail and a more realistic looking carrier deck.
Unfortunately, it was so long ago that I can't find any pictures of what I built. I do remember that you need a lot of gray bricks. I would recommend this set above all the other MegaBlok sets for replication in LEGO, as its a massive build and especially fun when built with pieces that actually stick together. And its a lot more fun to plan out all the LEGO pieces you need and salvage them from the Internet than to get them all in neat little bags.