I haven't read that thread but I think the answer to your question depends on how many people are traveling, their ages and what kind of food they like on vacation. If everyone is happy with counter service, basic grill food, sandwiches and pastas and/or if they are okay with sharing large portions, then I think you'd save a little but not a huge amount of money by eating at offsite restaurants vs. onsite restaurants. For the modest difference, enjoy the onsite theme restaurants and convenience during your park visits or at your onsite resort.
OTOH, if you have teens who eat & eat & eat... if you have a fairly large group... or if they like seafood & steaks... or if you really enjoy sitdown meals, where everyone gets their own selections, including beverages, appetizers, salad/soup, desserts (the whole shebang), then eating offsite will definitely save substantial ca$h, IMHO. Onsite sitdown restaurants cost more for theme and location and this $ difference grows with the size of your group and their appetites and tastes.
Crossroads area includes Pizzeria Uno, Olive Garden, Jungle Jim's & Denny's. If you happen to like the food at those and you have a hungry crowd, they may offer convenient dinners. If you want a breakfast buffet for a crowd, they are very cheap at many places on Rt. 192 Kissimmee and on Int'l Dr. Same for many very popular specialty & chain restuarants.
Traffic getting to/from the I-Drive locations is generally less than to/from 192. This is especially true if you are coming from the South I-Drive area, near Buena Vista Suites. If you are onsite for a major holiday (Christmas, Easter, July 4th, etc.), I wouldn't bother with the offsite traffic at all during the holiday dates - stick with onsite or Crossroads. Don't forget that the hotels near Downtown Disney (Hotel Plaza hotels) also offer restaurants - some will have local coupons too.
