remote lag with my new home theater

Probably a symptom of your Pioneer as it's upscaling the Wii from 480i/p. I doubt it's the sensor bar, which is just an IR light source.

I don't run my Wii through a receiver, but a couple quick questions:-

1) Have you changed the Wii to widescreen? (Dumb, I know. But maybe...)
2) Have you adjusted the Wii remote sensitivity?
3) Have you tried changing the sensor bar position from top->bottom or vice versa
4) Have you tried "Game" mode on the LW5300?
5) Any lag with Wii component directly into the LW5300? (I'm guessing none/very little)

-vdz

I agree it definitely isn't the wireless sensor bar--it's merely a stereo beacon for the Wii remote to use as a guide, and the light it gives off is no slower than a Nintendo or generic USB-powered sensor bar's

I have a similar receiver, the VSX-1120-K. I don't know much about the 2011 line, but in 2010, the 1120 had a different video processing chipset than the 1020 and lesser models. The 1120 has a Marvell chip and the other models from that year have an Anchor Bay ABT-1015, which from my research prior to purchase seemed on par with the Marvell. Subjective arguments for the Marvell somehow cleaning up analog noise more effectively when upsampling to output HDMI was all I really came across, and I remain skeptical of those claims. I certainly didn't read about scaling delay issues. Your 1021 also has an Anchor Bay chip and I really doubt it introduces latency issues not found on the 1020.

I concur with trying Game mode on your TV, and of course try disabling scaling (set to pass-through) on your receiver as it's just a few clicks away. My bet's on the TV, though. Try to find out how much input lag your display has--it's probably documented somewhere on AVSF. It's more likely the culprit. Game mode on most TVs will minimize input lag by applying less post-processing (junk like 120/240hz upsampling you don't need for a game which doesn't play at a neat and constant 24 frames per second), but some odd TVs have other methods for doing this, and some, including those with lots of bells and whistles that are designed primarily for HDTV/Blu-ray playback, will have enough post-processing enabled no matter what to make games feel unresponsive. A pointer like the Wii remote or PS Move will exemplify the lag even more, as you noticed... It's not an issue with static content like television or movies, because you can merely delay audio by a fraction of a second on your receiver to sync them up. That doesn't work so well with a game you control in real-time :P I hope your TV isn't the most expensive component of your setup--it probably is, but it should be fixable.