The Asteroid map in question is Asteroids1. There are 6 different asteroid maps, Asteroids 1 through 6. Generally speaking, the higher the number, the more difficult the terrain, so Asteroids1 is fairly easy and light on asteroids. If you want a challenge, try Asteroids6 or Nebula6. For the most part, this is also the first time I've seen these maps as well in game, and I've already found a few of them that could be improved. If you have any map ideas, by all means make suggestions. We have 27 different terrain types to play with.
Regarding large maps... space is big... very big in fact. The larger the map the more realistic it is. I appreciate your argument about some players having developed tactics particularly suited to small maps, but by your own argument then, some races are also disadvantaged by small maps as much as large maps, as you have claimed. This being the case then it doesnt really matter what size map it is, someone somewhere won't be happy.
In practice though, SFB used both a 'floating' map and a 'fixed' map. When using a floating map, at the end of each turn, all the ships would be moved back to the centre of the board, thus making a limitless sized map. The fixed map meant if you reached the edge, you could disengage. Tactics developed for small maps are not the only tactics available however. Boxing people into a corner was not something you did in SFB. Larger maps require that you use your weapons as they were intended, plasma ballet, sabre dancing etc. Use of terrain is also a critical feature, we have more than just rocks to contend with. Small map tactics can be adapted to larger maps quite easily (especially if there are ion storms around). I am sure a player of your calibre will have no trouble with this.
The only real disadvantage I can see to large maps, is that if you do have to fly off the map for some reason, it can take awhile to get there. Overall, however, large maps are better, more realistic, and reflect the fact that space is very big and where practically possible the game should try simulate the laws of physics. I thank you for your concerns over large map size, but try to give them a go, you might like them.