Relative Difficulty of PRNG abuse for shininess

I'm going to exclude Gen III here explicitly because (P)RNG abuse there is tied to several factors that make it quite hard from the start.

One of the main benefits of (P)RNG abuse, that is, changing the date and time of the DS in order to get previously calculated results due to the predictability of the games' pseudo random number generator, is being able to encounter shiny Pokemon at will. This is especially interesting for Legendary Pokemon who you can't simply breed with the Masuda method for a few weeks until you hatch a shiny offspring. So this question is going to focus on abusing the PRNG to encounter shiny stationary Pokemon such as Legends, Driftloon in DPPt or Lapras in HGSS (among others).

Between Black, Black 2, White and White 2, nearly all Legendary Pokemon exist in Gen V. The same is true for Gen IV thanks to Platinum and Heartgold/Soulsilver. For the few who are only available in one Generation, there is no choice. But for the others, assuming access to any game, I can choose where to RNG my Legendary to get it as a shiny version.

Now what I'm wondering is where this process is actually harder. Initially, I thought Gen V RNG is generally easier because everything can be done with Non-C-Gear seeds, which are set based on the second alone, while in Gen IV you have to hit a delay, which limits the error margin to roughly 1/30 of a second. However, in Gen V the portion of the PRNG responsible for generating the PID is apparently subject to an inconsistent offset and hard to check. I've also read somewhere that it's not advised to go for perfect shinies in Gen V unless you also RNG'd your Trainer IDs.

Here's the question. What difficulties do I have to overcome in order to encounter a shiny stationary with random IVs in Generation IV and V respectively?
If you can answer that as well, I'd also be interested in a comparison of how good I have to be in some area or another for one Generation to be easier than the other (e.g. "If you can hit your delay 1 out of 5 times, Gen IV is easier due to the constant starting frame.").

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Before anyone gets the wrong idea, I'm not interested in subjective answers of the kind "I think Gen IV is easier because my experience suggests that." You're welcome to post that in a comment, but an answer should list the things that make it hard to pull off in one or the other Generation. I can decide what this means in the end for myself and anyone who googles this can also make their own decision of which obstacles they'd rather learn to clear.
Also, I can see the topic of cheating come up. RNG abuse is widely accepted as a shady/questionable but not illegal or objectionable method of tricking the game for the following reasons. Since no external devices are connected and a computer is used for calculations only, the Pokemon received through this method are legitimately created by the game and could have been encountered randomly. The method boils down to calculating the point in time where the desired result is generated by the game and playing in the correct way and is thus very similar to looking up information about "secret" in-game events or mechanics in some guide or walkthrough.