Here's the comparison I see with the G3x vs. the HDX on plates. It takes fewer steps to access charts on my G3x MFD screens. The HDX, however, automatically puts it in full screen mode, which is nice.
Would the Trutrak have flown that approach vertically and laterally for you?
With regards to programming, why use OBS? Even if you're concerned about being vectored onto the radial before GINNA, you might as well use the VOR and then switch to GPS when you get the direct or onto the radial. The reality is that Mugu is always either going to give you a heading or a direct if you are GPS equipped, instead of dumping you somewhere on the radial. Why? Because the approaches into KCMA all go through that area. Vectoring you onto the radial would require crossing the approach course for both the VOR and RNAV Y.
As for the 2600 before the turn, I doubt that had to do with traffic. I'm pretty sure it had everything to do with his MVA. I fly IFR in and out of KCMA a lot. I never put together that they needed 2600 before turning me, but now it makes sense, cause that is usually the lowest I am before getting a turn (usually 050 and then a direct VNY, as I'm headed to V186 to get back to KMYF).
Legally speaking, you can fly that VOR-A approach using GPS as your primary navigation source, so long as you monitor the VOR as secondary. Since you have a VOR in your plane (2, actually), you're ok. It is the much better approach, as FlyingMonkey pointed out, because the cone of confusion really impacts safety there, especially in windy conditions.
As for an RNAV/GPS approach from the west into Whiteman, my guess is you're gonna have to keep waiting. There is no GPS approach at all into VNY, and I read somewhere that it is probably related to the terrain and traffic concentration in the area and that they can't really build new approaches. Your RNAV 12 has circling minimums, and they are lower than the VOR-A, but SCT seems to never want to give that approach.