(IMHO) If one were to do a side-by-side with these two, it would hardly be a fair comparison, even if the Pappy were "only" the 15-year.... Since more than half of the SB blend would be 7-years old or less. That said, the two pours would be similar enough that most folks would note the similarity. I don't think too many would confuse the two, however.
Now, if one starts to compare on a price/value basis the differences will likely shrink to insignificance for many folks. IMHO the SB blend is a rather better value and quite a wonderful pour, which I would take hands-down, if I'm the guy pulling out his wallet. ... Just sayin'...
Your price point is right on also. The on PVW I find in the San Francisco bay area ranges from $225 for 10 yr, $250+ for 12 yr. $600+ for 15 yr. ( Craigslist prices) That will buy a lot of Antique and 12 Year.
I think I remember someone on this site had blended Larceny with Devils Cut (3 to 1 I think). I tried a 1 to 1 blending and just tasted it last night. I was really surprised at how the Larceny lost its youngish taste. It was super smooth up front with a very comfortable oaky finish that I really enjoyed. The real test will be a re-taste and see if it seems the same.
My favorite home blend is 4RYL with OGD114 at 60/40. Tastes remarkably like ETL for about half the money.
And 4RYL is what?