Thanks for the replies guys.
R4 does look like a great alternative to ds-Xtreme.  Its ALOT cheaper, and i can buy as many micro-sd cards as i whish, to have as much capacity as i want.  

I do have a couple of questions for you R4 owners...
1. What does the 'slow booting', SirPoonga mentioned,  have affect on ?  Is it just the initial start up of the game, or loading of stages etc... ?
2. I have read a few reviews on the R4 and the only bad point is that the download compatibility suffers.  What are your thoughts / experiences on that ?
Any thoughts or comments are more than welcome.