The Lunt pressure tuned scopes have the advantage that the etalon is always perpendicular to the incoming light, rather than being tilted for tuning. This tends to give a larger sweet spot and makes double stacking much easier down the track.
Matt Wastell has some images with the Lunt 60 scope here:
http://www.iceinspace.com.au/forum/s...ad.php?t=91941