I looked hard at the RD NS 9 but went for the RD 9 again as could get only one. I was getting a a few things when sales were going on, I gave half of my new OKC knives away to people who I knew who could use them. My little brother was the biggest scorer from me as I gave him a few of my surplus blades, it should cover most his out door needs for a long time. I told him to mix and match what is best for him and if some thing he don't use as often, STILL keep the low used stuff as it may come in handy.
I'll probably get another RD9 or RD 7 next if can before they are all gone. The RTAKII will still be available is one reason I never got one yet. The SP-51s going bye bye made me concentrate on them. As with the SP-53 still being available I gave one to my brother in place of the intended SP-51 I was going to. The SP-51 isn't the chopper the SP-53 is but field wise its easier to maintain and still just as good batoner. The SP-53 and SP-51 are my dedicated heavy use woods blades. And I mean HEAVY USE. It replaces a hatchet for me on most outings as for me its safer to split wood with batoning it, for bigger expeditions or longer ones more wood killing stuff comes along.
The RD9 for me is becoming the general purpose one take all with a light knife along for GP stuff. As its more multitool than a dedicated woods chopper. The RD9 is a knife that can chop and do some woodsy bushy stuff. The SP-51 and SP-53 are choppers and can do some knife stuff, the SP-53 seems to do it more better because of its blade re-curve where you can use different parts of the blade and angles of it to do things with.
Where the RD9 with its choil makes it like the other RD knives a decent, not good as a super uber niche knife uber thin breakable blade bush craft knife, do bushy stuff knife.
I figured out the reason I favor knives like the large real knife types. I remember the Finnish Sami knife a relative used and showed it to me as when I was more young and foolish and he told me every thing it has done, I tried to get one buy my old man was "Thats why to big of a knife!" said the one who made me gut a deer with a 1 1/2" inch victoix swiss army knife.... It does every thing the more "Modern" larger blades do, being it comes from part of my cultural heritage I guess it stuck in my head.
I keep an RD9 in my car with and RD Tanto for in case go off road in the boonies or break down. Since its a car an axe and saw also ride a long in it, and an SP-51/53 if I didn't take it out for some other task I really needed it for. Oh and a SPAX as it accidentally was in the car when some one needed to turn off some thing fast they grabbed it and turned it of guess they knew it could do that. So I keep it in the car now as well.