Although HD camcorders do require more light than SD cams its only really a problem in very poor lighting conditions. The lighting you get in sports halls and stadiums should be no problem, and I find that my Sony FX1 actually does very well in fluorescent lighting. At a recent wedding I had to wind the gain on my FX1 all the way up to 18dB because the lighting in the reception hall was atrocious - just dimmed tungsten lamps and candles. The pictures were a touch grainy but very watchable.
As for handling fast motion, it depends on which camera you have and which type of HDV it records in. JVC cams record in 1280x720 at 25 or 30 progresive frames/second while the Sony cams record at 1440(1920)x1080 at 50/60 interlaced frames/second (the Canon does both). There is a big debate about which is best for sports - progressive or interlaced, but the fact is that 25/30 progressive images looks juddery but gives you rock solid freeze frames, while 50/60 interlaced gives you much smoother motion but jittery freeze frames (but you can always de-interlace).
The bottom line is that 25/30 progressive is like film and can't resolve fast motion properly while 50/60 interlaced is like conventional (CRT) tv and handles fast motion much better, which is why I bought a Sony FX1.
As for HDV dropouts, I had a lot of these when I first starting shooting HDV because I used tapes from different manufacturers using different lubrication methods. Stick with one type of tape (I use Sony Premium) and dropouts, while always a risk, will be a rarity.
Do yourself a favour and go HD - the image quality is sensational.