This is going to be disappointing and anticlimactic to you guys following this thread but after hemming & hawing for the past few days on getting a work knife for Boxing Day, I finally decided on... a Wharncliffe Delica 4 (at 20% off).
I know, I know, it isn't a large folder.
I almost pulled the trigger on an Endura 4 in Zomé Brown and a Pacific Salt—both of which were added later in the week to my local retailer's Boxing Day sale list—but at the end of the day, it came down to being honest with myself and asking if I would get a fair amount of work utility from a big folder relative to the price (even at a 20% discount). And ultimately, the answer was "no".
There just isn't any work task for me that expressly requires more than ~3 inches of blade (or that couldn't be covered by the Polestar, the longest folder in my modest Spyderco collection). Add on top of that the potential hassle a larger work folder might draw from coworkers and managers who blanch at the sight of any work knife that isn't a cheap boxcutter and, well, I just couldn't justify the purchase.
I think a large folder would have ended up serving exclusively as an outdoors knife for me, and in that case, I prefer using a fixed-blade, of which I already have four Spydercos: a Waterway, a Schempp Rock, an Enuff, and a Ronin 2.
Earlier in this thread I posted about trying to avoid the collector's mindset, this notion of wanting something just for the sake of having it. I think I might fallen into that line of thinking with my search for a large folder, where I confused my curiosity about large folders with a need for a large folder.
Maybe I will revisit large folders in the future—the Siren looks like a good choice for an outdoor folding knife—but for now, I think I will continue to enjoy large folders vicariously through the posts you large folder-having guys share on the forum.
Thanks to all who took the time to participate in the poll and share their thoughts and suggestions, I greatly appreciate it all and even though I didn't buy a large folder in the end, your comments made me reflect on what it is I actually need in a work folder. And in a way, that is a much more valuable takeaway from this whole thing.