I must admit I have never actually used the XVive gear, this response is from reading the manuals online. I do have 8x channels of Line-6 in RF1 mode.

Excuse the poor english where I have cut-n-pasted verbatim from the manuals:

U2 1~4 channels are the same as U3/U3C/U4 1~4 channels,
U2, U3/U3C and U4 use in sametime max is 6 sets.

U2
CHANNEL1 2402MHZ,2480MHZ,2482MHZ
CHANNEL2 2408MHZ,2472MHZ,2474MHZ
CHANNEL3 2420MHZ,2456MHZ,2458MHZ ** THESE ARE DIFFERENT FROM U3/U4, MIGHT BE A TYPO
CHANNEL4 2432MHZ,2448MHZ,2450MHZ ** THESE ARE DIFFERENT FROM U3/U4, MIGHT BE A TYPO

U3
CH1 2402MHz, 2480MHz, 2482MHz
CH2 2408MHz, 2472MHz, 2474MHz
CH3 2416MHz, 2464MHz, 2466MHz
CH4 2434MHz, 2440MHz, 2442MHz
CH5 2427MHz, 2448MHz, 2450MHz
CH6 2422MHz, 2456MHz, 2458MHz

U4
CH1 2402MHz, 2480MHz, 2482MHz
CH2 2408MHz, 2472MHz, 2474MHz
CH3 2416MHz, 2464MHz, 2466MHz
CH4 2434MHz, 2440MHz, 2442MHz
CH5 2427MHz, 2448MHz, 2450MHz
CH6 2422MHz, 2456MHz, 2458MHz