I also have the Garmin Legend and I use the MetroGuide USA maps. I have not used Roads & Rec. so can not help you there.
The amount you can load does depend on the area that you are loading. ex. Is it a city or rural area. To load the Detroit MI area it takes 6.71 MB. The hole State of Alaska is 5.55 MB. As for the Colorado area I was able to load Denver Co. is 4.23 MB. This is an area of 100 miles wide by 70 miles high. I hope this helps you in some way. GOLDFINCH, Mason, MI