should i go with kt150's now or wait a bit??


simple question folk's,    I have two jolida 502 amps running in mono.  kt120 tube's with about 200 hours. just broken in lets say.  this is almost going on two years now so I guess Im not listening as much as I should be. I will take care of that!!    the amps are running the top end of my infinity 1b speaker panel's.   mid's and high's.  no bass work here. so the question is is it worth installing kt150's at this point in time.    for $600, I would need eight of them, what kind of improvement in sound would I get.  with just 200 hrs on 120's would you run them a little longer to at least get some use out of them.   everybody like's the 150's for the solid bass they get out of them but I would not see that running the mid/tweeter panel.   what would you guy's do if you had the $600 ready to go??  (don't answer that)   can we assume in time the 150's price will drop a little more and just wait it out .   I know it's such a tough decision here, just help me out ok. thanks
tomtab
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thanks everyone for chiming in.  all seems to be good now.  everything working ok.  8 hours on the 150's now and the mid/tweeter panels seem to be singing.  my cd player just lost its right channel, go figure.   a cambridge 840.  good player when it was working.  but i guess their all good when working.  looking at the net I see they have problems that have popped up and i guess mine has some of them.  and that what happens when you buy a $1,200 cd player,  they shit the bed like everything else. and getting it fixed is not going to be cheap.  o well
I switched to KT 150s from KT 120s and while I prefer the 150s all around, it was not the huge improvement I expected. Had I known, I would have waited till my KT 120s were fully used (they only had about 800 hours) before making the move. Changing capacitors and power cords had a greater effect to my ears.