All of the Remington M700s that I own I bought from about the early 1990s to about 2004 or so. Out of these guns, I have only had 1 major problem, and that was with a BDL SS DM in 7mm-08. The trigger was so bad that it actually swayed left and right like a belly dancer. Given that I really wanted to take that gun on hunt the following week or so, and given that the gunsmith said that Remington could not replace that trigger within such a short period of time, and given that the gunsmith said that the trigger could not be fixed with a simple trigger job, I went ahead and had the gunsmith replace the belly dancer with a Jewell trigger.
Other than that, the usual work that a newer M700 needs is just a simple trigger job and perhaps a recrown, just like I have done with most, if not all, of my 700s.
Now, my father has an older 700 BDL Deluxe in .30-06 from about the late 70s to early 80s. It has a metal butt plate, so you can imagine how hard this gun kicks. Anyhow, working the action on this gun is truly a pleasure. It is as if it was customized by the finest gunsmith. I say this because none of my newer 700s actions feel as good. I have even had some of my newer 700s customized by having the bolt and action jewelled, but the bolt still does not cycle as smoothly and precisely as my dad's older 700.
Is this to say that the older 70s and 80s 700s are of a higher quality than the newer 700s? If I had to answer than question based on just comparing all of my newer guns to my fathers just 1 older gun, then I would have to say yes. HOWEVER, it really is not a representative answer because I have not had personal experience with many older 700s.
Graybeard has probably owned more 700s, both old and new, than just about anybody I know, and, if my memory serves me correct, he generally believes that there is no noticeable difference in quality between the older and newer rifles. Over the many years that I have been a member of this site, I have learned to value and respect his opinion. While I may not agree with him on everything, it seems that we do agree on about 95%+. So if there is an area that I don't have personal experience, then I usually defer to him.
You may also want to talk to EXPERIENCED gunsmiths and ask them their opinion on this subject if you want. I emphasize "EXPERIENCED" because it seems that just about anyone nowadays seems to call themselves a gunsmith, even with just 1 year of training. Find someone with many years of experience under his belt. We can learn alot from those with wisdom.