Thanks all - v helpful: some of the Qs are those I'm pondering on already, others are things I hadn't thought through fully (the benefits of asking!).
So for the missing info, apologies. I'm building up my rig slowly (and within a capped budget). Scope is a TV102iis, currently just on an alt-az mount (WO EazyTouch, but the original version built by Beat Kohler at AOK) <-- so no go-to or auto-tracking capability (yet). Most of the viewing is currently lunar, planetary & the brighter stars (lots of light pollution in the city) - but its a mobile rig, and I will be using it in darker skies eventually. Current EPs are 4mm & 6mm Radians, a 13mm Celestron plossl and a generic Barlow.
I did my first proper view w the Radians on the moon a few nights back. Wow - I'd never seen the moon like that! Sharp. The difference in power between the 4mm & the 6mm was also quite something.
I do find myself preferring some eye-relief (I prefer to take the instajust out a bit on the Radians) - I wear glasses (although I don't use them - so far - for viewing through the EPs).
The difference in quality (sharpness etc) b/w the Celestron & the TVs was palpable. But the lower power of the plossl was helpful in making navigation quicker. So I know I need to get a better quality longer EP (13mm or more).
Tbh I haven't been planning to spend on an EP the amount that even a used Nagler costs (capped budget). And so I've been looking more in the price-range of Baader Hyperions. But then when some used Delites popped up (admittedly slightly more expensive than a Hyperion!), I realised that that's equivalent to 1 Nagler cost-wise...
Maybe I should be self-disciplined and just get 1 Delite, and save the rest for a the future (like a 3.5mm Nagler ).
Anyway, there you have it. Will look a bit more at the Morpheus & the colour rendition link on the Delites.
(PS - Edited addition: the other thing crossing my mind is that eventually I may want to try putting bino-viewers on this scope to get full immersion, and so maybe having Delites is better for that budget-wise!)
(PPS - another edit (so much great feedback): yes the re-balancing is something I'd rather avoid - switching between the 13mm plossl to the Radians was enough to whack the balance, and needed re-nudging and/or tightening of the clutch. With no encoders, I'd prefer to not have to do that too often in a night!)
Edited by vineyard, 10 October 2019 - 05:59 PM.