I would say unless you absolutely need the /G filing capability I'd just take a handheld GPS and rock it VFR. The last time I shot a no kidding GPS approach by necessity was in March 2012. I do make use of terminal /G capes fairly frequently. But I suppose one could feign /G capabilities by filing /U and asking direct anyways for the few times you need to file IFR. I have no plans on shooting a SID or STAR out of busy airspace in my ratty spam can (that's just work) and most places I go to have an ILS if I need it. The rest of the capabilities I make use of in the G430W I have in the airplane, I also have in the monochrome GPS196. LPV is not a necessity for me either. I like the 430W and perhaps it will come in handy on the 2020 ADS-b conversion, but if it hadn't already come with the airplane I wouldn't have it installed in my aircraft.
I did remove the 89B from my previous airplane with the intention of installing it on my next aircraft. Since the replacement came with the 430W, I sold the 89B and associated components. Otherwise I would have installed it. I actually prefer the King logic (since I teach to a KLN900 at work). As others have said, updating the 90B is a PITA. The 900 (militarized version of the 90B) has front loading card. The 90B does not.
If you can keep the installed cost below 5K I would say it's a nice addition. But that's also going to depend on what airplane we're talking about and what is the intended use. Most people don't fly IFR substantially enough to justify their panels.
