I’ve one, highly rate it. Super easy to install and remove, sturdy enough that I removed a second clip on the pannier bags. Looks well smart.
But to your questions, about the mudguard, not sure, I have the lightweight option and it might get a little tight, imagine the bigger rack would be ok. Dedicated pannier attachment? Are you on about ql3? I use ql2 and it’s fine, mainly for urban and a little bit of gravel. I think if it was MTB I’d have to put the second clip back on the bottom, so there’s one pointing forwards and backwards like their “gravel” panniers.
Slight hijack, can anyone recommend a similar quality front rack?