Upgrade From SME IV to V - Worth It

IMO upgrade the phono stage you get much better results

@mgattmch The Gyrodec is a fine turntable. You can not do better without spending insane amounts of money. I know your cartridge well. What I would do is keep the IV and replace the Maestro with a Soundsmith Voice.  The Voice is as good as many highly touted MC cartridges. It is high output so you will have an excellent signal to noise ratio and it's tracking ability is unsurpassed and it is much less expensive to re-tip. 

It depends initially on the period of origin of the IV, initially the V had Abec 5 bearings while the IV had Abec 3 then over time they made improvements to the entire V IV and 309 series.
I would keep the IV replacing only the original wiring with pure silver and investing the money saved in an upgrade of the head or phono.

the V has some more features as standard (silicone damping tank not necessary because if badly adjusted it suffocates the sound) possibility of VTA on the fly, lower tolerances than the IV but not to be heard obvious differences that do not let you sleep at night, VDH cable in silver; according to several enthusiasts who have had the V it seems to sound more  soft compared to the IV but these are nuances.
Changing the head for the better you notice more differences than going from the Sme IV to the V

Many thanks for everyone's input/advice. The general consensus of opinion is; keep the SME IV. Good advice, which I plan to take. The suggestion to replace my Clearaudio Maestro V2 Ebony MM cartridge with a Soundsmith Voice MI cartridge is interesting, will follow up on this.

I recently purchased the Analouge Productions UHQR The Doors LA Woman disc. I honestly don’t know how a 53 year old recording can sound this good on a 33 1/3 vinyl disc, simply mind blowing! Surface noise was non existent, dynamic range was outstanding as was frequency response. Overall, the best vinyl pressing I have ever heard. Also worth mentioning, packaging and associated printed material for the new disc is simply outstanding, as good as it gets IMHO

I recently purchased the Analouge Productions UHQR The Doors LA Woman disc. I honestly don’t know how a 53 year old recording can sound this good on a 33 1/3 vinyl disc, simply mind blowing!

no, it's not amazing, it's analog and that means investing in the components that make up the turntable is very important.
Even on vinyl records from specialized audiophile houses dating back to the 70s, listening to them today you are surprised at how good they sound.
Vinyl has everything you need, the enthusiast just needs to be able to find the way to extract everything that is inside the grooves.
It's a shame that current commercial or audiophile vinyl pressings have reached unaffordable prices.