Anyone with a recommendation for a #fountainpen? I've been considering getting one and just completed my self-imposed two-month test run with a disposable Pilot Varsity with satisfactory results. Here's what I'm looking for:

Something fairly slim, say 11mm barrel or less
Vacuum/plunger fill, piston would be a reasonable alternative
Flexible nib would be a plus

So far I think my best option might be a used Conklin Nozac Vest Pocket or perhaps a Sheaffer Balance Slender. I don't mind a little DIY effort, but if it'd take expensive specialised tools to maintain an old pen, then maybe I'm better off looking at newer models. What #fountainpens can the Fediverse recommend?