I've been using the Boulder 1010 preamp for the past 18 months and I'm extremely happy with it (not looking to replace it). I think the phono stage is quite good but it's shortcoming is a lack of flexibility. I've considered adding on a separate phono stage. Boulder is rumored to be working on a 1000 series phono stage but they tend to be very slow to come to market with new product so that could be years away.
I'm curious to hear the experience of any 1010 owners that compared the phono stage to an outboard unit ie. Einstein, ASR, Blue Amp, etc. If I decided to add on an outboard phono preamp I would want it to be fully balanced.