A bit OT, but as I see this article being referenced in exactly the wrong way time and time again ...
#1 There is no such thing as a 100% consistent version of "The Fluff" - you will find contradictions on a great many topics, including Space Marine power levels. Hence, the definition of what an "actual SM" is would have to be very flimsy indeed.
#2 Games Workshop wrote its fluff for the game, not its game for the fluff. The idea that they would intentionally write the fluff in a way that would not fit the game seems weird to me.
#3 Said fluff includes a number of instances of Marines getting pwned by anything from Orks to IG to rebellious PDF, up to and including a Marine Commander getting strangled to death by a human officer. Said instances just seem to get ignored by their most vocal fans, or more likely they don't bother to do the research (in their defense, this stuff is usually "hidden away" in the codices of other armies, or issues of White Dwarf - reading Marine stuff alone will only show you one side of the coin).
Indeed, a number of things in the "backstory of the universe" would be impossible using the rules from FFG's interpretation (where Astartes can solo Bloodthirsters).
#4 If GW had wanted to portray SM as tougher in the TT, they could have easily chosen to do so with a simple points adjustment and still maintain gameplay balance. I posit that the tabletop achieves its balances not by nerfing or buffing individual units, but by using points values resulting in numerical differences.
#5 The Movie Marines rules you are referring to specifically point out that they are based on, and I quote, "the concept of dramatic license, an amusing little technique that involves exaggerating or ignoring facts, physical laws, and general plausability to keep things entertaining. Space Marines are embellished in fiction, where their heroism and invincibility are accentuated."
So the Movie Marines rules are actually evidence against this idea. It is ironic that, most of the time, they are posted as an argument for better Astartes. The rules are called Movie Marines, what do people expect?!
There is no "right" or "wrong" here - Space Marines are as strong as you, the individual reader, want them to be. That's how 40k fluff works. Careful reading in GW's own material would result in noticing that they are a lot more vulnerable there than what I have seen of most 3rd party material, be them Black Library novels, videogames, or the Deathwatch RPG.
Ultimately it depends on which origin of sources you as an individual consider most important. For me, it's GW, as that's the stuff "I grew up with". And for this reason I just can't get used to the more powerful interpretations from various novels or FFG's RPGs. For this reason I applaud ideas and projects such as the one from SgtLazarus here that aim to cater to the more "classic" version of Marines, which I maintain fits better into a setting where the Astartes are just one piece of a puzzle, instead of the shining star around which everything else is supposed to rotate.
I will address more points when I get more time, but on #2 and #4, GW only does rules changes for one thing, to drive sales. You can't make money if your most popular army requires 10 figures that costs a person $50. Much better to sell them 50 + vehicles for $400+.
#1 and #3 Fluff varies, but you go with the most common and likely. Genetically engineered, indoctrinated, superhuman warrior monks are going to be significantly more powerful than Guardsman.
Rogue Trader (TT wargame) dropped out of the fluff a long time ago. Sadly Marines are no longer convicts strapped into power armor with augments and let loose on the enemy. Of course, it TT, the standard human is only 16% less tough than an Ork, and equally as strong...I don't think basing fictional units power levels on tabletop balance for a game based around marketing more miniatures is the best way to go. Hell, they remake entire editions just to sell things that either aren't selling, or to introduce a new mechanic just to sell more.
#5 Movie Marines: Yes, they are following the marines of the fiction over the tabletop rules, or anything involving reality. Marines are 7-8 foot tall monsters that spit acid (Dependent on chapter, this gland may not function), have massive skeletons with a fused ribcage forming a plate of bone, and can eat their enemies brains to gain some of their knowledge. They also have the standard 2 hearts, 3 lungs, etc. Combined with the other implants I am going to go out on a limb here and say they should be significantly faster, stronger, tougher, than a Guardsman.
In the end he can do his Marines any way he likes. But we are all free to discuss them.