It's all a matter of taste. Is it worth it to you? Nobody can really answer that.
I replaced mine with a set of Bareknuckle mules and I'm very happy with them.
One thing I would suggest is try adjusting the pickup height before you go buying replacements. This can have a dramatic effect on tone and hardly anyone seems to bother.
On the opposite, meanwhile nice pickups I do find a reason to change them, I find MKII a bit shrill on the top end. But I usually change pickups on my Tokais if the guitar is VG or excellent *58 Pretenders, Dr. V, Throback SLE/101 plus, Shed Paff Daddys.... I have a Duncan 59 MJ wind period correct 80' s set I am about to try in my Reborn LS80......
I agree with luis. On both my ES130 and LS150 I also found the MKII too bright and perhaps a little bit lacking in body. Now have Manlius Fat Diane's in the ES130 and Lollar Imperials in the LS150 and feel that both guitars have experienced a significant upgrade. However as others above have stated, I would first persevere with the MKII's as they are quality pickups in their own right.
As guitar players and collectors I often feel that we collectively are a marketing man's dream (!!) and are often a mite too hasty in throwing our cash around in the never ending guitar upgrade spiral... Also I am an acknowledged PAF pickup tart (have had experience of: Dimarzio PAF's, Seymour Duncan 59's, Fralins, Lollars, Manlius but my absolute favourite brand are Deacci ((formerly RD Pickups)) ).
Lots of info in this old thread: http://www.tokaiforum.com/viewtopic.php?t=14270&postdays=0&postorder=asc&highlight=wizard&start=45