I have no personal experience with the Hansen Prince speaker but reading the specs 87dB and 6ohm nominal seems like borderline case with the Shindo. I pulled up the Stereophile review and in John Atkinson's measurements section, he measured the Prince's sensitivity at 85dB a little lower than Hansen's stated rating of 87dB, however, importantly the speaker does not got below 8ohms between 10-200Hz in the bass region so it will not present a difficult load in the bass region. It does dip below 4ohms in the mid-treble region and up (from about 2.5KHz and up)never going below 3 ohms it looks like. This suggests that with a tube amp, the high frequencies will be a bit of a tougher load on a partnering tube amp and may be somewhat attenuated. Here is the relevant section from John Atkinson's measurement section:
"My estimate of the Prince's voltage sensitivity on its tweeter axis was a little lower than specified, at 85dB(B)/2.83V/m. This speaker will definitely benefit from being driven by a powerful amplifier, particularly as its impedance (fig.1) drops below 4 ohms in the mid-treble and above. The impedance rises with decreasing frequency below 1kHz, which means that tube amplifiers, with their relatively high source impedance, will sound heavier in the bass than solid-state amplifiers with the Hansen. But as the Prince V2's impedance at lower frequencies doesn't drop below 8 ohms, this speaker should work well with tube amps."
Here is the impedance and phase angle graph across the frequency spectrum:
http://www.stereophile.com/images/archivesart/408Hanfig1.jpgMy suggestion, take your Shindo Sinhonia amp with you to the local dealer who carries the Prince speakers (if you have someone locally) and try them out. You may get a sonic signature that you like but purely from the impedance graph it sounds like you may have attenuated high frequencies/treble and heightened bass response with tube amps, which may add up to a warmer than tonally neutral presentation.
As for the sensitivity (85dB-87dB vs. your 40wpc amp), if you are in an average-sized room and don't listen at crazy SPLs, you should be able to drive them adequately. But again, if you listen to a lot of rock and like to listen at concert levels than you are likely going to run out of steam with this pairing. Again, take your amps to a dealer and try them out. That will be the best way of determining their compatibility.
Hope this helps.