I never was able to solo EE anything, but I did farm multiple epic items on EH, including bracers of twisting shade. So it's possible.
Unfortunately you're already in a build that is suited to shiradi, so it won't really get better in a different life. I would try to grin and bear it to max shiradi now.For whatever reason, I'm finding Shiradi not so interesting. Maybe it's the randomness of the damage effects. I'd like to get Nerve Venom, but nothing else is left to really excite me. I may switch out of Shiardi when I get to Tier 4 and move back to LD and take that to Tier 5. Devastating Critical and Master's Blitz are calling me. I could really use the extra 100 HP that LD is giving me too. Tier 1 Avatar is done, I'm 900k into Shiradi, so not far from Tier 4 now.
When I maxed out shiradi I did it on a longbow ranger build and found it to be acceptable, if not great. The +4 ranged power from cores (same as Shadowdancer, double the +2 from LD cores) is the primary benefit. As for abilities, I kept Double Rainbow stance active and used the active attacks Pin and Otto's Whistler. Everything else was basically an afterthought. (Mostly spent my AP on dex, as I was a dex build.) I'd advise it's worth another shot (no pun intended) on this life.
As for blitz in LD, it doesn't synergize all that well with a great crossbow. You may find it difficult to raise the stacks above around 5 (of 10) and having it expire completely between fights, though it's always great for long boss fights. Its charges are granted on a per-hit basis, so it works great for repeaters, shuriken throwers, and TWF melee builds. For THF, longbows, and great crossbows, with their slower rate of fire? Not so much. And keep in mind that blitz starts with -12 ranged power compared to shadowdancer and shiradi because LD only gets +2 RP per core instead of +4, so the first 2 stacks of blitz are needed just to break even. I'd rather you play around with blitz on a combat style that's more suited for it so as not to sour you on blitz altogether.
Regarding destiny feats, yeah, they're mostly for melee. PTWF grants +5% doublestrike to all melee weapons regardless of combat style, so that's a no-brainer for all melee. For ranged, the clear best #1 destiny feat by a mile is Doubleshot, but that requires two Primal destinies. Which brings me to...
Fury of the Wild is actually pretty solid for a great crossbow build. Adrenaline -- granted immediately in the first core ability -- is a single-shot active attack that does large damage, increasing as you get more cores. It's got a delay, in that you click it, your character freezes for a full half second, then your next attack of any kind includes adrenaline. When the destiny is maxed, the adrenaline effect is +16 crit range and +400% damage, which for a great crossbow means guaranteed crit, and the damage is 4x a normal crit, 5 times per rest. In tier 5 you get to take Fury Eternal, which has a chance to recharge 1 adrenaline use on vorpal, and your great crossbow build vorpals on 19-20 so that's a total win. You'll want your adrenalized shots to be as damaging as possible, so try to only do it with Wracking Shots (+1[W]) or Leg Shot (+2[W]), tiers 2 and 4 in the mechanic tree respectively.
For ranged builds, the epic past life from primal is much better than martial, so you may decide to switch over from martial to primal for your first epic past life. If you do, max shiradi and fury and take doubleshot as your level 28 destiny feat.
If not, I would just take shiradi to tier 5 for fate points (maxed if you can stomach it), then switch back to shadowdancer for the rest of this life and reincarnate at 30 back to 20, then either run another epic life or TR back to 1 into something else.