Yes, I have some input on that. I've owned quite a few of both types. The late-model M39's from the 60's and early 70's have all been very good to excellent shooters with the ammo they favor. Usually good quality light ball. With handloads you can usually get some near MOA or better groups. I've had problems gearing them to work with the D-166 loads for some reason. They seem to favor light ball so maybe that's what they were being built for. Also the bores are sometimes a little on the tight side so you can shoot .308" bullets in them to great effect. My current 1970 is doing remarkably well with Barnes .308" TSX, but cruddy with the usual stock of .311" and 312" sierras and horn. bullets. It has expensive tastes. I'd say these are more collectible in general, but there were also some really rare subtypes of M39 during the war like the Tikkas and the straight bolts The only big drawback with these is they tend to have cosmoline-infected stocks because they were never given a wood finish before being dunked in the grease. If you get one, get one with a DARK looking stock, not the blonde one. The dark ones did get some covering for the grain so they're not nearly as inflitrated with grease. I had a blonde stock that I swear had two or three pounds of cosmoline inside its grain. Took over a year to leach most of it out slowly and it got lighter and lighter!
The M39's from the Continuation War era obviously include quite a few in well-worn condition with used bores. Do watch for splitting in the wrist of the stock. They were running low on good wood by that point or something, because split wrists crop up. I've had good luck repairing them with rods and glue, but you can see the repair marks. In very general terms these seem to do better with the heavy ball than the late model ones. But as always each Mosin is a new slate and you have to figure out what it likes. You will often find a series of shims in these which were used to tune the rifle to the load they were using at that time. Overall, though, I'd say the average accuracy of the wartime M39's is not as good as the late model so-called "sneaks." This is doubtless due to the wear and tear of combat. If I were to get a wartime M39 I'd get one of the SKY Civil Guard models, because they tended to be pickier about their rifles than the regular army.
I have had no dogs with any of them, compared with a pretty high amount of barking with Soviet Mosins. I avoid the fixer-upper ones these days and try to get the most pristine. The guy your looking at there is a great seller and I've bought from him five or six times in the past. He doesn't try to sneak in junk--he tells you exactly what you're getting.
Personally, off that list, I'd get this one in spite of its high tag:
"Unissued 100% original blue, blazing new bore, matching bolt, unnumbered floor plate and a sky 43 war time stock in new condition."
