wave-based respawn, coupled with well designed maps, introduce a great deal of tactical elements that simply never exist in Counter-strike. I've played Firearms, and Firearms is definately not coupled with well designed maps.. or good gameplay of any sort if you ask me. The maps are extremely linear, fighting occurs in the same places over and over. Ambushes in unexpected areas or flanks are very rare. Also, when you ARE flanked, combat occurs at such a sluggish and clumsy pace that it's rarely worth it to ambush in the first place. The combat is repetitive, and unexciting. I don't remember seeing a DOD-like capture and hold system, either.
In CS, most servers enable "kill indicators" that appear in the top right. Thus, as time progresses, you constantly have a general sense of just how many enemies are left to deal with, and how many allies you have. DOD feels a lot closer to what a real war situation would be like.. you have a fog of war, you don't know what areas of the maps are being attacked in greater numbers than others, and camping positions are always changing due to the fact that battle lines are being redrawn every second. In CS, when both teams spawn, they have a rough estimate as to how likely it is for an enemy to be in a certain area, and so it's not uncommon to see the same areas being fought over.. again and again.
Another symptom of round-based games is that they do tend to have VERY simplistic maps that are often balanced so that both teams don't feel cheapened by certain powerful positions.
And again, the idea that wave-based respawn makes people behave tactically different is just not true. It has no basis, and if you watch people play DOD, you can see that their thought processes are identical to that of round-based games like CS. The only difference is that in DOD, the same processes occur much more often. I played CS for at least a year before making the switch to DOD. I haven't missed CS since. (if you haven't played DOD, you need to. Although it took a severe quality drop with the retail release..... and it is a requirement to download custom models/sounds and especially maps before the game really shines.)
This all being said, it's a shame other wave-based games like Enemy Territory don't take their system to their logical advantages. In ET, people keep respawning, and then going through very linear motions to attack the enemy objectives. If ET had a capture and hold system, things could be a lot better.