Indeed… we have two 3G mobile services, and one ADSL service.
Does this mean we like 3G twice as much as we like ADSL? Absolutely not. The vast majority of our business is conducted over the ADSL link, with the 3G services only being used when we're not at home.
Mine personally, gets used prominently for APRS-IS traffic, so that family members can check where I am without needing to actually ring me. If there's a big download spree, it'll be at the end of the month when I've got to find about 1GB of data that I can download to use up the remaining quota.
There are a lot of things I do on the ADSL link, that cannot be done over wireless, especially not with the plans that Telstra offer (Carrier-Grade NAT sucks worse than dynamic IPv4), and while the speeds on the 3G plans are faster, the quota is a lot less, with a heavier penalty imposed when the quota is exceeded.
If a carrier offered a price-competitive service with which I could run my server (i.e. static IPv4, ideally IPv6 too, and no firewalling of ports or SMTP blacklisting), and without the latency, maybe I'd consider it.