I recommend the Hinderer over Strider if you can get it direct from Rick. The XM-18 is not worth the inflated prices in the secondary market when could get you a fine custom or nearly two CRKs for the money.
When I first started hunting for a Strider, I ran into lots of issues with lockup. I wanted one of each of the PT, SNG, and SMF. My PT had up and down play and some stickiness but lockup was overall secure so it was not too big of a concern to me. I only sold it as I prefer other folders in that size range. I went through three SNGs with horrible lock slip problems until I found one that was solid. Note that the three that failed to lock up properly all had the new lock geometry. I sold the good SNG anyway as I prefer its bigger brother. My first SMF had up and down play which generally worked itself out after breaking the knife in. Sold that one for my second SMF and the only Strider I still own. It has an aluminum scale instead of G10 and an M4 blade - love that knife.
I only kept buying Striders as I liked the ergos and figured I should have at least one in my collection. But all in all, it still amazes me the kind of following they have considering their QC problems. For $300+ "hard use" knives the lockup issues are laughable. The die-hard Strider fans are very vocal and can tout the Strider warranty as much as they want - there are definitely better buys out there for the money. I am patient and knew the negatives going in which is why I kept looking despite one bad example after another, but I only own one now for this same reason.
As for Hinderer, the XM-18s are nice knives assuming you pay the direct price. I have an XM-24 with rock solid lockup and good overall F&F. If you are looking for a flipper, be prepared for a bad detent and thus weak flipping action. My XM-24 suffers from this as did the many XMs I have handled. I chuckle every time someone mentions that Hinderer does this by design but take it or leave it. I purchased my XM-18 as a "pimped" knife with modified detent which now flips properly. Again the lockup is dead on. I have never dealt with their customer service but it generally gets positive marks from the community.
Neither the Strider nor Hinderer is going to really outshine your CRK. Strider ergonomics are fantastic if they fit your hand but be prepared for disappointment with fit and finish or lockup compared to your Sebenza. Best bet is to purchase secondhand when the seller can confirm everything is good to go. The Hinderer is superior IMO. I like the options to customize your XM with the various scales, parts, etc. Keep the detent issue in mind though. If you cannot get it direct from Rick, it would be wise to look in the midtech or custom knife world at that price range.
As you mentioned, I love the looks of the knives from all three makers. Good examples from each are going to be super tough and should perform equally well for the average user. From the sound of it, you will most likely end up owning knives from all three companies anyway. Happy hunting!
