If you talking about one of those Ex-Snipers with the original tap holes welded - they are more desirable, but not necessarily worth more.
If you ever get a chance to hand select, you can usually find 2-3 in a crate of 20x rifles. I would rate them as rare as a hex receiver. The 91/30 site rates them as a 5/10 on the rarity scale.
They usually have better bores and might be slightly more accurate as they were selected for their accuracy at one point in time. I do find that the bolt is much smoother on ex-snipers.
PS use to sell them for a premium price - either $50-100 more than a standard 91/30.
I found two on Thursday at Milarm, but only picked up one.