Both are excellent speakers. Be careful about version I vs version II of the Grand Piano. I liked version I a lot and my limited experience with version II is positive as well, but of course version I is no longer current and should sell for reduced price.
Don't be to quick to sell the Dahlquist IMO. I think you'll find that certain speakers of that era capture a lovely musicality that modern speakers don't always match - and the DQ-10 is one of them. Don't assume that you will prefer your new speakers until you break them in thoroughly (crucial!) and then do a comparison.
I have owned 7 pairs of Thiels and yet continue to use my oldest pair, the 04a's, in my office. It's the warmest and most forgiving. My 20 year old Gale speakers don't offer the resolution of my modern Thiels or Spendors or Proacs but they are thumpingly musical and lovely.
For either the SGP or RR3, the quality of your electronics will be crucial. The RR in particular seems to be very sensitive to quality of electronics. I have heard the RR sound spectacular (at the Red Rose store in NYC) and heard them sound just ok as well.
