I'm starting to feel this way as well; the SB seems really cool but as it stands I'm not sure the hardware is ready yet. Feels a lot like the original SP. A bit ahead of its time and I think future iterations of it will be the way to go.Maybe the SB2 will get it right for my needs.
I had initially planned on getting the SB with i5/8/256/dGPU, but at the end of the day I think the i7/16/256 SP4 is the better deal for me. The tablet functionality is important to me and having to manage 3 hours (probably less) battery life on the SB probably wouldn't be very pleasant for me.