I just got an email asking about the UKPK, so I thought I would just post up my response:
Well, the UKPK I have is the discontinued G-10 version with s30V
steel. I did own an FRN UKPK for a few months, but I gifted it to a
good friend for Christmas. The FRN UKPK was still a very good knife,
but there are a few differences between it and the G-10 Version.
First off, the steel is BD-1, which is good, but not quite as good as
S30V. Second, the backspring is not as strong, which both makes it
open faster, and close easier than the G-10. Now this is both good
and bad, because it is very easy to disengage, so I found I was using
the choil and my index finger to hold it open a lot more than on the
G-10 version.
It does have some strengths over the G10 version too however. It is
dramatically lighter because of the FRN scales and the smaller
backspring. It is one of the lightest knives I have ever owned, I
never really felt it in my pocket at all. The FRN scales are really
nice too, they have a great texture that simulates the feel of G10,
which is one of my favorite handle materials. The wire pocket clip
works really well with it too. It is a very fast knife, allowing it
to be used and put away in a flash, which can be handy for escaping
notice if you don't want people to see you using a knife (more as a
public comfort thing, not weapon, I think this would make a very poor
weapon).
Overall, I think the FRN UKPK is a great value. For EDC tasks, the
lack of a lock really doesn't matter, and in fact makes it easier to
use. Some locks can be a bit of a pain to disengage, and sometimes
even dangerous (liner locks can be really sneaky about biting, due to
the extra force to overcome the detent while having your thumb in the
way.) You don't need to put your thumb in front of the blade to close
it, which I love. The FRN now comes in black as well, so you have a
lot of options. As for blade style, I owned a drop point FRN, but my
G10 is leaf blade, and I really like that shape, but I don't know
which is better in a saber grind (mine was Full Flat Grind).
Hope this helps!
Also, I just wanted to tag on that if you want an even smaller lighter
slipit, the Spyderco squeak is excellent. It has a 2" blade, with a
very similar design to the UKPK. It has the same FRN, and a bit
sturdier of a backspring than the UKPK. Also, it comes with a full
flat grind blade, and N690Co steel, which is between BD-1 and S30V.
Its a tiny champ lol.