Calculations
I think you need to do some tests and calculations.
1. Ripping, encoding and transferring many disks is labor intensive and time consuming. Wouldn't you rather be watching movies?
2. How many times are you realistically going to watch these movies on your iPad -- as opposed to a proper TV from a Blu-ray (best experience)
3. Perhaps it is worth it to simply rent or purchase the titles you really want in HD from iTunes, Amazon or another source.
My .02
I wouldn't bother with a Blu-ray rip for an iPad. I'd only watch it on the big screen. I'd rip DVDs of some of some titles, then rent or buy HD versions of others as seems appropriate for content. If anyone can report back here with quality of ripped blu, ripped DVD, iTunes standard and iTunes HD comparisons appreciated