uboot, we are kindred spirits. I implemented this a few days ago and wrote essentially the same reply as you yesterday, but it was lost after I got distracted for a while and then submitted it after I'd been auto-logged-out. My current compromise differs only in that I've mapped the page-left (105) button to SPACE and left the right one as is.
Not the most elegant solution but it is quite functional and well worth the loss of "page-back" functions, since I tend read in a mostly front to back fashion and there's always the touch screen for back-tracking.
As jr points out this is purely a matter of preference and I'm sure many will elect to keep the stock keys. For me though, the primary benefit of remapping is that the keys can be used to minimize scrolling and turning animations and imprecision in several apps I use.
My current button uses:
Stock page-forward (106): Turn pages in Sony Reader and CoolReader, and page-down in stock browser.
Remapped SPACE button (105): page turn in Kindle App, next item in Google Reader/Gmail, and general page-downing in pages and lists (especially useful for me in root explorer and various menus).