I would agree that your serial number places your SP101 in the first year of production and likely within the first 8,000 made. Is that rare? I don't think so. I've never heard anyone state that the first 8,000 (or 1,000 or 20,000 or whatever) SP101s were better than any other. 570-00001 would be rare - the first one. After that the collectors have more interest in the duplicate serial numbers (ie. D570-04461) or the used serial numbers (ie. 570-26390U) or the guns with unique and scarce features (like the French contract SP101s with a lanyard loop.)
It's not like wine. 1989 is no better a year than 1999 or 2009. Besides, how "rare" can something really be when you're talking about one of over 40,000 now made (and climbing)?
Yes, all SP101s share the same sequence of serial number sequence regardless of caliber, barrel length or other features.