Now here's my question - will I notice the improvement
enough? I've had several OM's tell me that on SSB, CW
or HF I would but not on 2m/440 simplex and repeaters.

Well, a 6 dB boost would double your range, IF you aren't hitting the limits
imposed by your radio horizon. VHF and UHF don't "bend" much, so once you go
beyond your radio horizon, you're pretty much done, no matter how much
signal you had. It will improve your signal into repeaters, where you were
a little noisy before, you should be quiet. On simplex, you'll notice
better signal once you get far enough away that you used to be no longer
full quieting.

In an FM receiver, there is a signal limiter, that caps the signal level, so
if you were already "full quieting", then no amount of power increase would
result in a better signal. If you are far enough away that you're not full
quieting, then yes 6dB will be noticeable.


--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR