connecting to multiple hotspots

It's different because you're talking about bonding - which is not viable over 2 connections to 2 different ISP's (unless the OP and his neighbour use the same ISP, this is the situation he will be in) - as it requires the ISP's kit to (a) support it and (b) authorise it. The later is certainly not going to happen with your neighbour's account ;-)

What I'm talking about is load-balancing (or teaming as the software mentioned calls it) over two disparate connections. Bonding was standard in ISDN TA's/routers of the day, whilst the load-balancing was, and is, used to combine multiple POTS lines or when ISPs did not allow dual channel ML-PPP ISDN connections.

The software (proxy/router) presents one connection to the user, whilst the actual Internet connection uses multiple connections - this is the same with both POTS/ISDN and multiple IP interfaces. The only difference being that the latter is simpler as no modem/TA drivers are involved, just native IP interfaces. The front-end software, which is essentially what this thread is about, is the same.

The manual and configuration screens, appear to disagree with you. Most of the WAN connections documented are connected via standard NIC interfaces (e.g. DSL, Cable, etc.) - the same presentation that the software would see with a pair of WiFi NIC interfaces.

The mechanism is essentially the same for client presentation of two load-balanced POTS connections as it is for two load-balanced LAN/WAN connections.

The client only sees (and cares) about the one gateway address. The software proxy/router handles the rest. The "hardware" devices that do this are only called "hardware" devices because they are in a separate box. The software that they run is similar to the software required to do the lot on one machine.

The major difference between the two is the market. There are very few SOHO users who need to load-balance over two "broadband" connections on one machine. Hence, the solutions for this tend to be high priced, aimed at multi-user LANs and sold in separate boxes to justify the price. That does not negate the fact that the mechanics and the software are substantially similar for a single user on a single machine as for 1,000 users on a LAN.