This somewhat depends on the local environment with the academic affiliate.
Lots of people where I am shift back in form in terms of FTE between the university and VA. The university, if you are tenure track, considers you full time in terms of benefits regardless of ratio. If you hold a VA grant, say a Merit Review (their equivalent to an R01), then you must be 5/8 VA. There are some oddities with colleges of medicine such that the hours you have available for work (VA = 40, always) may be asymmetrical (e.g., COM at a university might equal 55, or whatever). Thus you can have some weird FTE divisions. For us, VA grants count toward tenure. Thus, a merit plus an r01 = tenure, ir two r01s or 2 merits. On my CDA 2 (VA equivalent to a K), I did do a day of clinic every other week at the VA. I stopped doing that some time through my grant to focus on grant submissions. I do maintain a minimal level of clinic activity on the university side still. Though, I mostly view it as an irritation. It is interesting in the moment and a headache administratively.
I see the positives as access to a different clinical population (veterans . . . I have TBI grants in play, for example. . . that works well in VA population), and access to VA grant mechanisms. For example, the CDA-2 pays more than the equivalent NIH K mechanism. Funding lines are roughly equivalent these days.
There are negatives:
VA system isn't really setup with academic types in mind. They tend to be a bit rigid on things like "tour of duty." And the red tape is. . . impressive.
Regarding salary, it is purely based on when you got licensed. Get the psychology dept in the VA to board you. It will be GS 13 plus steps for years since license that you will get credit for.
Too many masters. Lots of people pulling on you.
I am severely over extended. But, this isn't a VA issue, this is a me issue. "I've got an idea. . . ." Everyone nods: "That's a great idea." Administrators "$$$$$$$$$$$$$$$$. Do it." Rinse, repeat.
Other things to consider:
Getting Merit level grants at VA qualifies you to apply to be a research career scientist. This is the VA's version of tenure, in a sense. With this, you can get beyond Gs-13 to GS 14 and above. That's a nice bump.
The TSP system is solid.
With that said. I'm soft money. My K will run out soon, so I figure I will soon be "retired."