Latency should be just 2ms, compared to playing thru plugins and >7ms latency ( on my setup), it feels lot better. I would recommend using reverb to give the sound more "room". I have loaded in 3rd party impulses, which I use more, but some of the cabs in radar aren't bad at all.
While I do not have much experience of using real power tubes, the simulation on this pedals doesn't seem too good. It helps smooth out harshness, but it also alters the tone alot, which is of course desirable, but the change is bit too exaggerated. I would have liked to see a dry/wet slider for how much you want tube effect.
Editing patches on radar itself is simple and fairly fast, and importing your own IRs is easy. Editing on external editor is a breeze, except for EQ, which design is full of bad decisions.
This is a pretty ok solution for jamming thru headphones, for recording when there's no access to better gear and space, or have as a backup for a gig. Tho this definitely isn't a replacement for a real cabinet in terms of sound and feel. It's lack some features other units have, which I would like too, but it's adequate if you just need something simple, or already have attenuator/dummy load for your amp and just need something to house the IRs.
EDIT 27.7.2022: I haven't really used this in years, but decided to give this a go for fun. What I immediatelly noticed is that the dial has gone really bad. Turning the knob changes the just about everything else than what you want it to, you try to cycle the patches forward but it goes back, you try to increase master volume a little bit, but it decreases by 20 etc etc. I don't know if it's just my pedal, has it taken hit during storage, but it's basicly unusable at the moment, except with editor.