Good to hear from you. (*Would one of these races happen to be The Rut 50k!?)
I'll chime in a bit, because I feel like kicking the subject of shoes around a few. It's been a while!
La Sportiva X-Countrys (**discontinued now, but the Anakonda is the nearly identical replacement) are very flexible and nimble with gobs of traction on just about every surface. These have been my default shoe for the shorter technical climbing runs recently and might do the trick for some of your upcoming runs. I did a 9 mile run in them last week with some really techy rocky sections and a short stretch of mixed surface (jeep road) at the end. I haven't run in a shoe as confidence inspiring as these for loose trail conditions, but the lack of midsole cushion really limits the distance these maintain comfort (13 miles is about my limit!). The forefoot room in these is adequate but not generous. I'd say they're medium volume and hug the foot appropriately, considering the shoes intended purpose. The lack of upper overlays keeps them from constricting the forefoot, so there is room for your feet to move around, but the fit is lightyears away from sloppy.
The La Sportiva C-Lite 2.0 could be a solid option for your races, merging much of the original C-Lite protection and cushion with the lightweight/nimble nature of the Anakonda/X-Country.
You're absolutely right regarding rocky/talus/scree underfoot conditions. Mountain running wasn't really they're intended purpose. You can stumble your way through rough sections due to the large contact patch of the outsole and the ample cushioning, but it can be a sketchy ride negotiating techy bits in these cruisers. If conditions get wet and muddy, particularly slick granite.....fahgettaboudit! I was slipping all over the place last year at the R2R2R.
I'm wrapping up my fourth pair of the gen 1 Pure Grits and I'm overall pretty stoked on that shoe as a door to trail shoe, but the outsole is the achilles heel. I've read the Pure Grit 2 has a considerably better outsole pattern, but the compound Brooks is using is still pretty anemic.
Some other options for you to consider:
Trailroc 255 (*read Tom Caughlan's review at iRunfar.com)
Pearl Izumi Trail N1 (*I only have 3 runs in these so far, but I'm pretty stoked on these right now) The outsole isn't overly aggressive but handles our dry rocky trails considerably well, much better than the Pure Grits.