I think you have just answered your own questions.
If you're into dance / trance, you'll need a tight low end.
1029's have, if I remember right, 40w at 8 Ohm low and 40w at 8 Ohm high. The 25's are 100w and 50w at 8 Ohm, which is a very big difference, with the 25's low end having well over double the capacity.
This is why I started my last post by saying "designed for surround monitoring with a 1091A matching sub" The 1091 sub is designed to provide the 1029's low end, not the 1029 itself, which is very plain once you look at the specifications of the amps.
The 25's are designed as stand-alone nearfield monitors first, which is why they have heavy low end amplification, like virtually all other such monitors. In surround configuration the 25's are matched up with an LSR12, which will give you an idea of their power, as the 12 is a real building-shaker.
Note that the above is just technical fact, not my opinion.
My opinion - you'd get p'd off quickly with the lack of bass from the G's, and if you try to compensate by pumping up the volume, you'll ruin the tonal balance.
Second part of your question - "nice" sound. I know G's are amongst the most popular monitor manufacturers, so I'm fully aware I might go a bit against the grain here. But - I am by no means the only person with this opinion. G's sound nice. Everything you play on them sounds nice. Note - I'm not saying good. Good = accurate, if I screw something up, I like to hear it, thats why I use expensive monitors. I want things to sound nice when I'm finished, before then I like monitors to just represent the truth.
The above was first just my, and some of my collegues, opinion. But - I work both as a recording engineer and as a mastering engineer. Every project I do I make sure I get project details, including which main / mid / near monitors were used. In time this gives you a pretty good picture. Tell me what monitors a project was referenced on - I'll tell you in what frequency band(s) I'll have to make corrections, before I have heard the project.
In the old studio we had a large spectrum analyzer, which had coloured markings under the frequency bands, just for fun. Each colour represented a type of monitor - deadly accurate.
Reason for the above, it proved my feelings about G's.
Hope this answers your questions, if not, just ask