Want a non-expensive rear light for the roadie…not for full-on night use – just to be a bit more visible in shite daylight.
That’s a bit of a contradiction. To do any good during daylight, a light needs to be brighter, not dimmer, than one you’d use at night. At 7 lumens, I can’t see the Femto doing much good during the day.
Smart Lunar R1 is nice and bright and can be had for not much more than a tenner (or £4, if you don’t want the bracket http://www.planetx.co.uk/i/q/LISMRTR1/smart-r1-luggage-mounted-rear-light-without-bracket ) but the sealing is terrible, and won’t last if it’s in the firing line of a wet back wheel.
Moon Shield 60 would be my recommendation if you can stretch the budget a bit. Can sometimes be found for around £30, very bright, USB charge, and I’ve had no problems with water proofing.