I have gone/been going through a similar search recently to mount a light on a Tubus Logo Evo. Before I share what I learned, I do have a couple questions/comments
1. Is this the Logo Evo or Logo Classic? I ask as apparently the Logo Evo has width limitations on the rear blinky that prevent some lights as they would interfere with mounting of panniers in the furthest back position.
2. What don't you like about the PDW Radbot that you are looking to replace it? I only ask as its will help direct what options might be good. Radbot was one of the options I narrowed down to. Positives for me being bright (but not the brightest), good/eye catching blinking patterns, rack mount included, inexpensive, and built in reflector. Negatives for me being not as bright as others now, batteries vs USB charging, physically very large.
3. I assume blinking is a requirement, ruling out the B&M options.
4. I assume USB charging is required, vs batteries, based on you comment on removing for charging
I started with a PDW Radbot, but am not 100% happy with it for the reasons I mentioned above.
I eventually decided the Cygolight HotShot might be the best option for me (at least to start with). It is very bright (noticeably more than Radbot), configurable, USB chargeable, etc. Unfortunately the rack mount was not included, but it wasn't very expensive to order on their website.
Depending on how that works for me, I may try some other options, such as the Planet Bike Superflash series - they have some USB options but not sure how good they are. Bonus is they supposedly work with the same mount as PDW lights.
I really like Light and Motion lights VIS180 and 180 Micro, but they don't seem to have a rack mount option (I saw one once but it seemed rather flimsy). The Serfas USL-TL60 looks like a great light, but not sure the simple rack mounting (a single screw) would work well on the Logo, nor would it make charging easy.
Sadly many other great lights do not have a rack mount option.
I hope some of this helps, and I am curious to hear what you research as led you too and what you finally decide on.