Chuckled over Barlow Bill's post! At one time, I had over a dozen Barlows and could have used a “Barlow Roger” moniker! Alas, I decided that I had too many eyepieces and Barlows and winnowed stuff out. I let go several that I should have kept.
I figured out something key — by raising the two of the tripod legs slightly, I could eliminate most of the droopsy problem caused by the Xcel 3x Barlow with the Astroscan. So, I likely can use the Xcel 3x for planets, on occasion. But a shorter one could still be useful.
One big advantage to using a Barlow, as I understand it, is that it changes the effective focal ratio of the scope, thereby cleaning up some eyepiece aberrations. In essence, with a 2x, the Astroscan becomes an f/8.5 and with a 3x, it's f/12.7. Or, the Z100 4” f/4 becomes f/8 and f/12.
Still, I like the idea of getting a shorter focal length eyepiece as futzing with Barlows is often a nuisance. Many have Barlows or Barlow like lenses built in. As noted, they would be smaller and, by having a shorter moment arm than an eyepiece-Barlow combo, would cause fewer issues. I could also pair it, as needed, with a small, light, shorty 2x I have that works well.
In recent sessions under the stars, I've rediscovered that most of my observing is at lower powers, anyway, where a Barlow isn't necessary.
As to which 3x Barlow...
Lots of people like the Meade 3x #128 shorty. Thanks for touting it. I actually have it in my cart at an astro store. But I've owned it before. Now, the one I had may have been a bad sample, but it had field curvature issues on the Moon that other 3xs such as the 2.8x Klee and Antares 3x didn't have. The Klee, though, had vignetting or blackouts on the Moon, but that was with a 25mm eyepiece, so too long a focal length. I did note that the Klee required only slight in-focusing — a big plus — whereas the 3x Antares required HUGE amounts of out focusing, dangerously large amounts! That one also magnified more like 3.4-3.6x. The Meade 128 required lots of in-focusing.
I wonder what the closest Barlow is to the Klee these days. I don't see them come up very often!
I may just have to try the Meade, the Klee or both again, unless there's a more recent option!