I think one of the strengths of blogs is that you can share opinions and advice with other folks, so thank you for all the questions and advice and comments about moving Bobby and Maya into twin beds.
We opted to do this over buying another crib. Our crib was $300 and, now that the kids together have grown out of it, it was either move them into twin beds or buy another crib. Peter and his brother went to beds early (I think Robert was 8 months old). We decided that we'd rather spend the money for another crib on other items. Their beds are only 19" from the floor (including the mattress) so there isnt a huge fall, when you consider the height of toddler beds. Peter bought "invisible rails" for the sides, so, once the bolsters dont work, we'll move to those. (And, honestly, I'd like to see those go up sooner rather than later...)
The kids sleep better in their own rooms than they did before. In the crib, although they loved (and still love during naps) to snuggle, there wasnt a lot of room for them to move around. In their own beds/room, Maya can sleep without being woken by Bobby, who gets up a bit earlier than she does. And Bobby doesnt have to worry about being slugged by Maya, who just wants him to hush and go back to sleep!
As to what we'll do when they start to walk around... I have no idea! At this point, they love their sleep and want to go "night night". I'm sure that will change, too... I guess we'll cross that bridge when we get there!!!