Today I gave my Grundig Satellit 2400 and Satellit 700 their first head-to-head test. I tested AM, FM, shortwave, and SSB.
First on the AM side, both units had virtually identical sensitivity with a slight edge going to the 2400 on the lower end of the band and the slight edge going to the 700 on the high end of the band. Both are very sensitive units. In terms of selectivity, the advantage goes to the 2400 - both are equals at eliminating adjacent interference from moderate stations, but when trying to listen to a weak station next to a strong one, the 2400 has considerably less adjacent interference. The edge on sound quality however goes to the 700 both in wide and narrow mode. The 2400 only has a narrow mode.
FM was a more interesting test as results varied quite a bit from station to station and not necessarily at one end of the band or the other. Both did a great job with moderate to strong stations pulling them in very clearly. On the really weak stations though, the 2400 usually outperformed the 700 except for on a few select frequencies where the 700 actually did better. As for selectivity, the 700 seems to have a bit narrower overall IF bandwidth (when measuring how far away you have to tune from a strong station to make it completely disappear if there's no adjacent station nearby), but the 2400 does a better job of zero-ing in on a weak station next to a strong one. As for sound quality, there is no comparison - the 2400 thanks to its stereo speakers and tweeters blows the 700 out of the water for FM sound quality. Overall winner is the 2400.
On shortwave, the 700 wins in sound quality and raw sensitivity, but the 2400 is slightly more selective. On SSB, the 700 performs nearly as well as a low to middle-end communications receiver, probably the best of any portable its size. It has a very low noise floor and can make very weak SSB communications intelligible - ones which the 2400 doesn't even detect. This may not be a fair comparison though as analog sets typically don't perform all that well on SSB, plus mine I suspect is way out of alignment since I cannot make LSB communications intelligible no matter what I do (and USB is only intelligible when turning the knob towards the LSB end).
Also, the 700 has a better automatic RF gain control than does the 2400, and it has a synch detector (something which I haven't really played around with much).
In conclusion, both are quite similar in terms of raw performance with each having its own slight advantages in certain areas. The 2400 has the best FM section I have ever tested in a "portable" (though I'm not sure I would classify this radio as a portable) while the 700 excels on AM and shortwave, SSB in particular. Both are well worth the $350 to $400 you will spend to find either in excellent to near mint condition (if you're lucky enough to find them in that condition as both are quite rare anyways), and I rate them both higher than the Panasonic RF-2900/RF-4900 Command Series.