In the title, check to see if the "Palm" is actually a "Palma" match barrel. If so, jump on that thing like a dog on a T-Bone.
It's not a "Palma" barrel. Palma shooters typically have very long barrels (30") because of the crazy distances they shoot with iron sights and lighter projectiles. This is a short barrel with no iron sights.
Another plus might ne the stock. What kind of stock does it have?
As for the stock: it's listed as a McMillan stock by more than one source. If it's indeed a McMillan A3 (and there is more than one A3 variant) then the stock is worth $500+. Check it out for yourself, the lowest I can find any FN/70 A3 for is $520 up to more than $700... I'm not sure if links to vendors are allowed so you have do the searching.
The action is made by FN and is of known quality (undisputed). Controlled feed vs push feed is a matter of preference, but regardless the action is probably worth about $400 by itself.
The big question is the barrel, which is of questionable lineage and quality. Good? Good enough for now? Good enough for free
? If it is indeed a true McMillan stock and an FN action then they're giving away the barrel at the $750 sale price.
As for barrel length I'm looking at an article which lists muzzle velocities for the same loads at different barrel lengths: you lose about 25fps per inch between 20-25" with the 308 Win. Examples: 20" = 2592fps, 22" = 2646fps, 24" = 2694fps. I'll let you do the math but I'm betting that at 600-800 yards there are multiple factors that will be more of a problem than the 100fps difference in muzzle velocity (ie you).
You asked about upgrade path... with a McMillan stock and an FN action your upgrade path is eventually an upgraded barrel. 308 Win is not a "barrel burner" and the longevity is often listed as 5000rds. Quality optics are required either way.
Now for the downside: I definitely didn't like the looks of the ring formed in the brass from the link that Creeper posted. My guess is a bad reamer, but crap happens for every company. I'm not ready to trash a company because one anonymous person on the internet had one bad barrel (and was refunded his money). If this becomes a trend then that's a different story.
Here's my advice: get what you want because it's more expensive to buy something, be disgruntled, and then go buy what you really wanted later. If you're only buying the FN because of the sale then that's probably not the best reason. You don't sound thrilled about the Savage either, so maybe you should pass on that too. If the bolt bothers you now it's probably going to really irk you later. No problem, I can think of at least 3 other brands that are on par with these for price/performance.