Udyr is the only one who utilises it well. Wriggle's Lantern in general doesn't give enough sustain on its own for most junglers so the Spirit Stone is a nice contribution to that. In fact I think that Udyr is the only jungler who utilises Feral Flare properly.

The guide itself, however, is lacking. It's a wall of text and not even that long. I'd like to see some comparisons between your strategy and the vanilla trick2g one and explain why your choices are (generally) better. Also the whole disclaimer of "Your team will flame you" **** is dumb. Just tell people when this is a good pick and when it isn't. I, for one, would never flame someone for picking Udyr and doing this in general. I will flame them when they pick it when our lane matchups are already disadvantageous and/or we really need some Crowd Control.

tl;dr Invest more time with BBCoding, mostly images. Add comparisons between your idea and trick2g and explain why yours is better. Explain properly how this works, why it works, and when to do it (5WH). Lastly, mention who trick2g is because not everyone will know.

EDIT: Tryndamere utilises this strategy pretty well also.

I dunno about that. I've been running it a lot on Udyr (ranked and unranked) and it seems to work quite well. You can literally go from 1hp to full hp just by clearing camps. You literally never have to recall after an awry gank. You can return to jungle and come out in another lane at full hp. Passives make for faster clear and reliable jungle mana sustain which Madred's Razors lacks on its own. For an extra 700g, it's a really good investment.

Only downside I've found is that it does take up an extra slot for a while, but other than that, it seems to work well. I've been experimenting it on other junglers (mostly Xin Zhao and Nocturne) as well, though I think it works best on Phoenix Udyr.

I'm not saying this guide is good (it really isn't), but I think the double jungle item strat is pretty legit.

The whole double jungle item strategy is just bad. Don't do it.