by now I reckon you have the answers... I've only shot one indoor 5 spot, it was different, I'm hooked
We have a "shoot your way across Texas" (SWAT) where you travel to tournaments and your best 3 or 5 scores are accumulated to qualify you for shooter of the year. It seems that there are a lot of these shoots and I enjoyed it better than 3d (I'm old and have problems judging distance). Vegas is the only one with the "Vegas 3 spot" made it famous....don't know how much of this info. is fact, but hope it helps...was so hooked, bought some of the 5 spots and shot random practice sessions in the yard to see how I was progressing. I really enjoy it and hope you have had success...waiting on next season.