If a full DLive system with Surface is out of the budget, and you can’t reasonably go without a Surface, then I think the Avantis is a great choice. I would recommend getting the DPack addon however. While not inexpensive, it really is nice to have all those plugins available “in the desk” instead of using outboard plugins. About the only plugin I felt was missing from the Avantis DPack was pitch correction (which the DLive now has with the RackUltra FX card).
Also, I think you will find that you will be almost required to purchase the GX4816 stagebox with the Avantis - especially if you want to continue to use the ME monitors with the new console (because the GX4816 has a ME port built into it). Outside of the single SLink port on the Avantis, there is no way to connect ME units directly to the console without using a GigaAce I/O card. This means if you use the SLink port for the ME system, you can’t connect anything else to the console without purchasing additional I/O cards (like a GigaAce card). By using the GX4816, you can connect it via the Avantis SLink port, connect the ME units to the stagebox, and still be able to connect up to two more DX boxes (or a single DX32 box) to the GX4816 as well. That’s a lot of flexibility and expandability built into a single stage box.
As I eluded to, there are some features missing from the Avantis (when compared to the DLive). This isn’t supposed to be a complete comparison, but some of the big things that stick out to me is that the scene recall filter system is not a granular as the DLive, nor does it have “actions”, both of which makes automation much easier. While there is the Avantis Director software available, you can only run a single instance of it, and it has to share the layouts that the board has (ie you can’t design/use different layers on the software instance). This is less of a problem since Mixing Station supports the Avantis, but it is something to be aware of. Because the DLive allows multiple Surfaces to be connection, you can have multiple instances of DLive Director running, and the layers can be completely different from each other or other physical Surfaces.
Don’t get me wrong, the Avantis is a fine system. I used it for years before finally making the jump to the DLive system.
While I have never actually mixed on an SQ system, I honestly think I would find it be annoyingly limited in its feature set after being spoiled by the Avantis and DLive. The scene recall filter system on the SQ is barely useable (it offers almost no granularity), it currently only supports one show file on the console at a time, the amount of devices/software you can connect to the system is limited to 8 instances (bad if you want your musicians mixing their own monitors using software), and the buss system is not very flexible so it can quickly become a hard limitation depending on your needs, which invariably change overtime.
I’m happy to discuss specifics with you. You can always DM me.