W Mint Marked Silver Eagles

The "burnished" ASE is a collector coin. that said the only one with investment potential is the 2008 reverse of 2007.

The UNC Eagles are ' as said' a collector coin. Think of them as another incarnation of the proof Eagles, carefully minted one at a time, not in a batch like the bullion eagles. Boxed separately, so the coins do not come in contact with each other. Will they hold their value? Like proofs, probably. Are they an investment, again as said, probably not. The premium paid, takes the silver value out of play, so what you have left is a combination of intrinsic value and collector value.

Special process, special handling and low mintage, if you like proofs as an investment, these are essentially the same thing.

I'd say in general, no. I recently sold a number of proof sets for an estate. I was pleasantly surprised at what the 2006 set brought due to the scarcity of the 2006W Eagle (worth more than the gold coin in the set). But that wasn't the norm - the rest of the coins brought only a small premium over melt.

It is interesting why some silver Eagles are the price that they are.

The top Eagle is the 1995W proof. It came in the 10th anniversary set.
Has a mintage of 30,125. It trades between 3K and 4K.

Second Best is the Burnished 2008W even of 2007.
Mintage 47,000, it sells between $400 and $500.

Staying with burnish coins.

The 2006W, mintage 468,000. I have not seen one sell lately.
But it greysheets at $60 ... RedBook at $100

Burnished coin for 07, 08 and 11 are considered common.
Mintage from 400 to 800K

Then you have the last couple years
2012 mintage 226,120
2013 mintage 281,310
2014 mintage 249,752

All three of the above trade at or more than issue price.

IMO these last three years are worth watching. They have fairly
low mintages, for a series that is widely collected.

So, Op's question asking if "W" mint burnished coins a good investment.
I would have to say if you bought them all when they came out,
you would be ahead.