I'm looking at getting either the RS100 or RS300 myself... I suspect the RS200 is discontinued or being phased out.
It doesn't seem to be in the products list on the polar site:
http://www.polar.fi/en/products
Looking at the PDF manuals for RS100 and RS200, it seems that the RS100 won't do everything you want. It can display and record up to 99 laps, but after running you don't seem to be able to recall the ave HR, max HR and split time for every lap... just the summary and "best lap" data. For most people the RS100 is probably all they need, but maybe not everything you are after.
For more info, get a copy of the user manual:
http://www.polar.fi/en/support/downloads?product=&category=User%20manuals