Well,I'm personaly a big fan of HKN, but as many others I originaly used keyclone, as it was the solution most people recommend for a multiboxing noob..

..and to some points this is true and the realy 'big-feature' of keyclone: it has a graphical gui and for basic multiboxing it is quite quick configured..

..for me, I used keyclone from april 2008 till (I think) september 2008 and then switched to HKN.
This was mostly, because i began to use an FTL-System and wasn't quite happy how keyclone handles the setup of the keymaps (and mostly the hazzle this has, when you try to explain it to others..). So, when Anemo posted the original FTL-HKN-Thread, I looked at the code and imidiatly loved it...
...this maybe, because as someone with some programming experiences grasping the concept of the HKN-Language wasn't that difficult for me, so I tryed HKN and got my complete setup running after one hour :) (the command-reference and sample-scripts helped here a lot!).

Another thing what realy got me to 'never' change back, was, that Freddie was extremly openminded listening to my bramblings of which other features I would like.
And even not all of my suggestions where implemented (special FTL-commands ;) ), there was allways a good dialog about it, and I could allways see, how I as a user could influence the development of new feautures (like <IF Win...>,<If Mouse..>,<SetVar..>,<Templates>,<SetToggle>...).

..don't get me wrong, I absolutliy admire Rob (author of keyclone) for his support of this site, the developement of keyclone and the good support he gives, but what I was missing in keyclone was the lack of new features, to suite my more advanced boxing needs (ftl,virtualbuttons,mouse-overhealing..) and the fix of some bugs (i.e. r/l-modifiers).
So mainly I changed from keyclone to HKN, because I missed some features in keyclone and now I'm loving the freedom HKN gives me to do exactly what I wan't!

So what I would recomend:
Use the solution you like best (or fits your needs best)!
For me all (three) solutions (keyclone, IS, HKN) have their pros and cons and you simply need to evaluate which one suites you best.
..but since you already using HKN without a problem, and HKN has more feature than keyclone, I in your position wouldn't change.
And if you have any question regarding HKN feel free to look in the guide (see Sig.) or simply ask here (or the HKN forum), most HKN users are very friendly and will try to help you (as in all fairness most of keyclone and IS user also would..).