Utility of Meade 6.4mm SP in ETX-90EC

I'm a new sky gazer thinking of adding a Meade 6.4mm SP for my recently purchased, used ETX-90EC with 884 tripod. I have the Meade 26mm SP, a Meade 18mm SWA, and 2X barlow. The 26 doesn't provide decent views of mars or saturn. The 18mmSWA is much better, but I want to get shaper, more detailed images of planets and inside moon craters. Is the 6.4mm too powerful to be useful with this scope? Is 2X barlow use out of the scope's limits with the 6.4mm? I often use the scope in remote desert areas of S. California, which have very dark, clear, and seemingly stable atmospheric conditions. Also interested in filter recommendations, specifically a 30% polarizer and #8 yellow, #80A Blue. Thanks for any feedback.

At least in Ohio, the 6.4 was too much for the ETX under most conditions. But we have terrible skies. The 6.4 gives something like 195x (around 55x per inch) and I guess it would be useable on things like the moon and maybe Jupiter. Anything else was too dark. I stick with my 9.7mm Meade SP and it is perfect for what I look at with the ETX.

For planetary close-ups I use a Vixen LV 7mm with my 105 and I'm very pleased with it. If your conditions allow I think you could barlow the 6.4 but I think the small exit pupil will be very annoying. I don't use my 6.4 for that reason. I think the UWA 4.7 or 6.7 might be a good choice amongst Meade eyepieces.
Nico