I haven't read the whole thread, but my recollection is that, unlike the old generation Jadis mono amps (JA30, 80 and 200), the original Defy 7 was not an autobiasing amp and could only use the 6550 tubes. To use other tube types in it, you (or, if like me you're not technically inclined, a good tech) would have to go inside the unit to set the proper bias, not an easy job. So any shootout of tubes will, in my view, not be particularly reliable, and could in fact damage the amplifier. I would caution against it.
Also, from a quick read it looks like you're changing or looking at changing the internal capacitors, etc. in the amplifier. You should keep in mind that by doing this you are changing the sound from the Jadis house sound. You may find you like the new sound better, it may be a more "accurate" amplifier, but please don't call it a Jadis anymore. I've had friends who got modded Jadis amps and had those mods undone because the Jadis house sound they wanted was lost. Jadis may not have used the most expensive or transparent components in their amplifiers, but the components were chosen in part because they gave the designers the sound they wanted (and I'm sure cost had something to do with it). If you change that sound and don't like it, please don't blame Jadis.
Also, from a quick read it looks like you're changing or looking at changing the internal capacitors, etc. in the amplifier. You should keep in mind that by doing this you are changing the sound from the Jadis house sound. You may find you like the new sound better, it may be a more "accurate" amplifier, but please don't call it a Jadis anymore. I've had friends who got modded Jadis amps and had those mods undone because the Jadis house sound they wanted was lost. Jadis may not have used the most expensive or transparent components in their amplifiers, but the components were chosen in part because they gave the designers the sound they wanted (and I'm sure cost had something to do with it). If you change that sound and don't like it, please don't blame Jadis.