I thought I'd update, now that I've heard the I-7.
As it happens, shortly before auditioning the I-7, I bought a very nice used Moon I-5 from the same dealer. People interested in the I-7, who haven't heard it, might want to check out issue of Hi Fi +, the British mag, with the Chris Thomas review of the I-7. IMHO an even-handed and incisive review.
I had a couple of very nice hours with the I-7. My take on the I-7 is that while it is a fine amp, it has a lot of features and capabilities for AV and multichannel that don't interest me, but which apparently account part of the considerable price step up from the I-5. The I-7 does offer significant additional range of loudness and softness, compared to the I-5, within any given note or voice. Is that greater fidelity, or just a magnified effect? I'm not sure. Certainly, the I-7 provides great detail and transparency without harshness.
If you like the house sound, but need more wattage than the I-5, or need multi-channel application, it may be a good candidate, but there are a lot of very competitive near-reference integrateds in that price range.
On balance, it left me more interested in the updated version of the I-5, for my small room, quiet listening tendencies.
-paul-