I realise shooting in full RAW is the bestest but I'm interested in the other two options:

Following details from Canon 40D manual:

RAW = Approx. 12.4 MB (3888 x 2592)
sRAW = Approx. 7.1 MB (1936x 1288)
jpeg (large/fine) = Approx. 3.5 MB (3888 x 2592)

What I want to know is if you had to abandon RAW because you were running out of room would you choose either jpeg (large/fine) or sRAW? As far as I know RAW is every bit of data possible with no compression. What is sRAW? Does it retain the same editing qualities but just in a smaller ratio? And how bad is it to edit a jpeg? Does it really matter when you are only doing a few lighting tweaks?

Please bear in mind I'm not a fancy pants when it comes to super critiquing photos and looking for the tiniest evidence of compression. I'm just interested in hearing the pros and cons between sRAW and jpeg (large/fine).

Thank you.