Vintage strat Question

I am by no means a strat expert.

One of my buddies has a 70's strat with the original frets... Plays great... If it feels good, don't change them.  Also, I think the 4 bolt necks are more stable and technically the better design from the 3-bolt... But that doesn't mean the 3-bolts are bad.  My buddies rocks and is very stable.

4 bolts are the original ever since 1951 with the Broadcaster later named Telecaster.  In the 70's they revamped the guitar to give it a moder look.  One of the refinments was the 3 bolt neck plate.  As said before if you like the sound don't mess with it.  I will also add if its original or close to it definetely don't mess around with it.  From a Vintage stand point it is worth more stock then it ever will be if you start messing it up now.  I don't think they are in high demand in the vintage market but thats not to say it coulnt bring you a couple grand if sold to the right people.  BTW Fender went back to the 4 bolt design in the early 80's after the CBS sold the company to the Employees.  Its like a engine block are you going to get a better seal on the heads with 3 bolts or 4 bolt.  4 bolt with give every corner a better seal because you can get every corner.  But thats just my theory.

Stability wise there's very little difference if any. Three bolt strats are very stable if everything is fastened down properly. Sound wise there's none, except from one guitar to the next, regardless of the neck plate type.
Have a listen to Walter Trout's 73 strat and see what you think.
Fender's pickups were made exactly the same way from late 65 to late 74, same winders, same machines, same enamel wire,etc..
People just pay more for a 66 pickup than a 74 pickup because it has 66 stamped or written in some cases on the bottom. Other than that they're virtually identical.

I've played some amazing 70's strats and some pre cbs that were flat and dead sounding.
I think the biggest problem was that this was around the "heavier the guitar the better the sound" era and unfortunately some guitars fender was putting out were boat anchors.

As far as fretting goes, if your guitar is in pristine condition and it's a collector's peice then I wouldn't refret it. If it's in reasonably good condition with the average player's wear then a refret won't hurt at all. Refretting will usually take about 5% of the value off, which isn't much and could make the difference between a sale and a pass to someone who wants to play it.
The price of 74 and earlier strats has gone up a lot in the last couple of years as the pre cbs strats are bought up by collectors here and in Asia. Either way, the prices are getting rediculous on the pre cbs strats and as a result more players are looking towards the more affordable 70's models. A few years back I sold a 69 strat for 7,000 and a 70 for 3,500. Look at the prices on those today. A friend has a very clean refretted 74 that was worth about 2,500 a few years ago and was valued at about 7,500 a few months ago. Prices are still going up.
If you're going to play the guitar then I'd refret it. If it's all original and you want to let it gain value over time(and it will) then you might want to leave it alone and just put it away.