Ray's stuff is solid. His designs and approaches have made huge influences on the ultralight world. You have to pick and choose what of his methods work for you but I definately recommend giving the backpack kit a try. Though I have designed and made most of many of my own backpacking items, one of may favortite is the pack I made from his kit. When it comes to my winter kit (mild NC winters) I tend to go for the Ray Jardine pack. He provides the basic design for his pack and bags in his book Trail Life. I recommend the book as well.
Ray pushes no sternum strap or hip belt. His original kits were true to this. You did not get either. It looks like he has relaxed this a bit and now offers these in the kit. I have found his original size (smallest he offers) to be plenty of room for my winter gear...about 6.5 lb base weight with the foam pad inside.
Here is a pic on Dec 20 using the pack in Linville Gorge, NC. I didnt expect to find an unfrozen water source for the first 24 hours (which was accurate) so I started with 3 liters. With 2 days of food my packs weighed about 15.5 pounds at the begining of the trip. Linville has some rough trails and the pack performed like a champ. BTW I dont use a sternum strap or hip belt, I stopped using them after reading the book.
PS I would recommend getting his thread at least for the pack, it is stron stuff.