You can't always avoid using a remote link to a repeater.
That may have been true 15 years ago, but with the low cost and simple deployment of long-range internet link products now, use of analog RF links for linking a repeater to AllStar would just make things overly complex with reduced quality, reduced features and various other side-effects. A classic example of people using tools they know to 'solve' problems that are better suited to other approaches. Sure you can use a screwdriver to drive a nail, but why not first look into more optimal solutions?
So you use a half-duplex link node.
A half-duplex node should never be used to link two full-duplex systems. I've seen it done many times and it's a real Mickey-Mouse 'solution'. AllStar is a Full-Duplex system, and repeaters are Full-Duplex systems. Linking them with a half-duplex link results in major issues. If a half-duplex interface is used what will happen is that if anyone on AllStar is keyed up, the node radio will be transmitting and thus unable to hear anything from the repeater. If someone on RF doubles with someone on AllStar, no one on AllStar will know. And if multiple AllStar users quick-key without waiting for carrier drop the node radio will never go to Rx mode and never hear anyone on RF. Various scenarios can result where if everyone on both RF and on AllStar does not always wait for a full carrier drop ASL users then can only hear other ASL users, and RF users can only hear other RF users. That's definitely not the right way to set up AllStar, and contradicts the original intent of AllStarLink.
The only reduced audio quality I've observed has been on Echolink connections.
Adding additional analog RF paths will always reduce audio quality. Nothing compares to the audio quality of directly connecting a repeater to a URI and AllStar node that connects directly to Ethernet. Long-range wireless internet link products have come a long way in the past 20 years and are now a better solution in 95% of cases (ie. internet linking at distances of up to ~10 miles) than analog FM links. Analog FM may be better in some situations without good clear line-of-sight but the ~30dB gain of long-range wireless internet link antennas can go a long way.
See also Full-Duplex Communication - An Important Feature in AllStar Nodes