Personally, as an XM-only owner of all three sizes, I cannot see the point in buying the massively overbuilt knife and then installing a relatively fragile blade.
Neither do I see the point in the smallest 3", as too small for most rougher tasks, and only offers office workers a scale model facsimile.
The XM-24 is not much different than an XM-18 3.5" as for IWB carry, and one would be hard pressed to note the difference after a day of carry.
The Spearpoint the better cutter while still quite a stout blade compared to many, the Spanto thick edged and tipped for harshest use and only adequate for cutting.
I carry the XM-24 Spanto as I buy Hinderer for one of the toughest folders out there, able to take on what would give tough design 4" fixed blades pause.
And prefer no lockbar insert, as if kept clean and lubed, wear is highly overrated, and inserts move only impact to titanium from face of lockbar to behind the insert, anyhow. Otherwise only another complication to design. I carried an original AFCK from intro for over 10yrs as a work knife in hangars, and never noticed much deeper seating past what original break-in accomplished, as it was not left with grit grinding on the Ti liner face. The Hinderer magnitudes thicker and less percentage original engagement.
And hardly any above comment as to size will apply to those clipping in a pocket, as the larger likely a true ball and chain. Never could carry in such a way with advent of clips, whether due to going prone, or clip snagging and knife yanked from pocket in tight quarters, or pushed out when kneeling, bending, sitting, low crawling etc., and knives swiftly packed with grit.
With ANY frame lock, have tools and be prepared to adjust action to personal preference, as all are set for safety, not individual whim as for looseness of pivot or pressure of lockbar against side of blade and detent engagement. I find folk whining about such to grate on nerves, them simply refusing to see the world is not about their own personal feelings, and them apparently of the mechanical aptitude of a wallflower.
As for fatty 3.5" blades, just stay aware that the same thickness as an XM-24 in a shallower blade will mean more obtuse primary grind angle, and not as good a cutter as the larger version of same blade style. An example would be the adequate cutter 4" spanto becoming a marginal cutter in a 3.5" fatty.
Whatever you want is out there, current or not, I just received another never-used fatty spanto Mon. in the mail. My advice is 24 spearpoint for cutter, spanto abuser. If you look around, you surely can find a spearpoint 24 for sale, and also take-off scales for less than the $65 new if money is killing you. Of course, the longer you wait on out of print knives, the harder the search. There ARE dealers you have never heard of who carry Hinderer, and who have stuff not moving due to lack of exposure. I have found quite a few that way.
Decisions can be exhausting.
