okay so ive been going back and forth on this for a while and i genuinely cant make up my mind. flying mostly in a mid-size city, lots of apartment buildings, commercial wifi, the usual nightmare scenario for RF. ive got a freestyle quad running Crossfire on 915mhz for the link which handles the city pretty well honestly, but im also flying a cinewhoop sometimes where im using ExpressLRS on 2.4 and the behavior is just really different.

the ELRS on 2.4 does fine in open areas but the moment i get near buildings with a lot of glass and steel the RSSI tanks and i start seeing packet loss climb. switched over to a buddys 900mhz setup and same spots felt way more solid. obviously 900 penetrates better, not exactly shocking, but i wasnt expecting the difference to be THAT noticeable in practice.

i know the conventional wisdom is 900mhz for range and obstacle penetration, 2.4 for lower latency and cleaner link in clear conditions. but is anyone actually doing systematic testing on this or are we all just kind of going by feel and anecdote at this point. feels like every thread i read is just people talking past each other with different setups and locations making it impossible to compare

youre not wrong that its hard to compare, environment variation basically makes any generalized test meaningless. i did some semi-structured testing a while back, nothing rigorous, just flying the same route with Crossfire 868 vs ELRS 2.4 on back to back days and logging the telemetry. urban canyon stuff near downtown. 868 was consistently better through the dense block areas, 2.4 held its own once i was more in the open. the crossover point was roughly when i had more than one building face between me and the aircraft.

one thing that helped more than the frequency swap was tuning the packet rate down on ELRS. running 250hz feels snappy but your link budget takes a hit. dropping to 50hz or even 25hz in sketchy conditions buys you a ton of sensitivity and i rarely notice the latency difference in practice unless im doing something really tight. might be worth playing with before you commit to a hardware change

tbh i gave up trying to optimize for urban flying and just put Crossfire on everything. probably overkill for a cinewhoop but i got tired of second guessing it. the mental overhead of worrying about signal in the middle of a shoot wasnt worth whatever benefit i was getting from 2.4. YMMV obviously especially if you care about the weight penalty