I have a Canon HF G20 and have been quite pleased with video recorded with this camcorder. The HF G20 does have 32GB of internal memory (which I have yet to use) and dual SD card slots and is about $400 less expensive than the G30. However the G30 does have a 20x zoom vs. the 10x zoom on the G20. The G30 does have both a 1x Mini Advanced Shoe and 1x Cold shoe vs. the G20 which only has a Mini Advanced Shoe (Canon proprietary shoe). The G30 does have more effective pixels and an option to save as either AVCHD or MP4 while the G20 only saves as AVCHD. Two things that are nice about both are the manual controls and microphone and headphone and headphone jacks. Almost forgot that another difference between the two is that the G30 records 60fps @1920x1080p whereas the G20 records 60fps @1920x1080i.
However, as kanewolf suggested, a DSLR would give you the option of interchangeable lens which is huge advantage over the camcorder. I have a Canon T4i and the video quality is great. The T4i however was quickly discontinued and is now two models behind the current one.
I also have an older Sony, HDR-HC1, and between it and the Canon the Canon has better low-light performance.
Things I would look for, and consider important, in a new camcorder would be the sensor size (impacts the low-light performance and quality), manual controls (gives you more control over the shoot) and microphone and headphone jacks.