And you really think the UE3 is any better suited? No. Both engines can be modded to whatever degree the team needs. The mod team is lazy, and the mod is uninspired no matter what engine it appears on.
Yes! the UE3 engine is MUCH better suited!
To make a realistic game/mod (lets just call it a "TS" from here, short for "Tactical Shooter"), you need some stuff to pull it off, stuff the Source engine does not provide, but the Unreal engine has been giving us since UT2003 (since the origional Unreal infact if we dont count rolling hill landscapes, but can live with very polygonal landscapes).
We need landscape and support for large maps, and open spaces, Source does not do any of this, the engine can render some outside scenery in singleplayer, but we've seen time and time again that its just not working online (and a series of canyons is not a rolling landscape, just FYI), which is why every MP shooter on the Source engine is by and large set in urban suroundings, on fairly small maps with paths and choke points, surounded by fake backdrop, thats fine for CS, CS is just that and has allways been that, but if we are going the route of realism, then thats just not good enough, its only a small fraction of the possible combat locations you could think of and want to impliment.
The lack of scale and landscape is not acceptable for any TS.
Netcode is also a big problem, Hitbox detection for instance is absolute rubbish on Source! you may not notice it much playing CS or HL2DM, but with a TS the need for precision is much higher, and higher than Source will deliver.
Same with its "Lag compensation" system, whoever thought up that one should be hung from the nearest light pole, having to shoot at where the enemy just was, and not where he is right now is just not acceptable for a TS, again, we need more precision, infact, i'd rather see a bad case of warping than this in a TS!
Likewise the ping, a TS is by and large a fringe thing, usually having a small but dedicated community, but this also means fewer servers, and people having to play with higher pings as a result, Source hates high pings, much more so than many other engines (including Unreal), many other games you can ping 200 or 300 and still be good to go, but with Source, you want double digits and no higher than that, or the problems start to rear their ugly head..
Projectile support is also rubbish, Source bogs down very quickly with many objects in the air, hence its reliance on Hitscan weapons, or projectile weapons that fire very slowly (such as rocket launchers and the like).
But there is nothing real about Hitscan, and again, Unreal has used projectiles on automatic weapons since its inception and can pull it off!
HL2's movement system does not work well with realism either, has to be rewritten compleately.. and im not sure that would be legal, as i think its engine level code (by law, you may not touch engine level code unless you own a valid license for that engine, you may only build ontop of it).
And there are many other things i dont like, but they are personal gripes so i'll keep them out of the debate, but the lack of map size and real landscapes alone is enough to shoot down the Source engine as a good choice for a TS, you just plain need that, or you will end up with just another CS clone, and add all the others and you have a lame duck.
Imagine if RO only had maps like Danzig, would it really have been any different than DoD:S then?
The Source engine is great at what it does, and if i was making a story driven singleplayer mod, Source would be in the top 5 engines i'd considder using, but for MP it has several problems due to its netcode, other engines are just plain giving us the same or more, and better, and you cannot deny that, it doesen't give us anything special, it does not have support for massive player counts, it does not have have a high tollerance for bad connections, and nothing we have seen thus far could not just aswell have been made on any number of other current engines (hell, i bet CS could run fine on the Doom3 engine.. not that i'd ever considder that one for a TS either, but you get the point, one could make a CS clone on that engine and it would work just fine), it is not a unique and beutifull snowflake!
And for a TS, Source is out of the question! its just not scaleable enough, trying to simulate real life is the hardest thing to do with any game, and you need a "jack of all trades" engine if you are to have any hope of doing it, Source is definately not a "jack of all trades" engine, it is definately geared twords singleplayer, with run of the mill MP support added.
UED 2.5 is a much better choice for a TS than Source, and now we're getting UED 3.0, and it looks to me it will be even better suited than 2.5 was, thus far atleast.