Agreed, superzooms are great in bright light, but like any compact P&S usually fall short indoors. Their "Superzoom" feature certainly is useful, and you can't beat their HD video with stereo audio, but they fall short of DSLRs.
If you really want a good superzoom, perhaps you should consider the SX-30IS from Canon, or the wonderful Finepix HS-10 from Fuji. I really like the feel of the HS-10, it feels the most like a DSLR over all of the other superzooms. Perhaps it's because of it's zoom ring and MF ring on the lens itself, as opposed to the little mechanical thing that usually is present on superzooms where the power switch is on the HS-10. The SX-30IS is very nice, especially it's EXTREME 35x optical zoom! You can't go wrong there!
DSLR wise, you won't be able to afford much with your budget. The only DSLRs that you probably could afford would be the Nikon D3000 or Canon 1000D, with only the kit lens which certainly aren't telephoto lenses! Plus, they don't feature video or many other neat tricks of the superzooms. Although, with a DSLR you can get OUTSTANDING low light, the ability to change lenses to get just what you want, use filters, get a shallow DoF, learn more about photography, get a better VF, etc.
Now, if you were just purchasing a camera for the safari and that's all, a superzoom would probably fit you best. I mean, you can zoom right up to the animals and even film them with HQ video if they're doing something that a photograph just can't show alone. Also, since a safari isn't indoors, you could get great outdoor photos. Now in the long run, a DSLR would probably be better. When you want to do indoor shots (Which would be often), a DSLR would get much better IQ. You can get some cool macro shots, make use of polarizing filters and do all that kind of creative stuff when it's needed.
In conclusion, I'd recommend a DSLR for you. Although it won't be SUPERB for your safari, it will take wonderful shots and be more usefull in the long run (IMHO).
Gear: 7 Nikon Nikkor AI-S and AF-S lenses, SB-700 flash, Nikon D7000, Nikon FM, variety of accessories
"There are no rules for good photographs, there are only good photographs."
- Ansel Adams