See, that's the only thing that concerns me about the idea of a chess clock as well. What do you do when one person has run out their half of the clock. Because even then, you could have a strategy of trying to make your opponent use up their clock time first. Even if you've used 25 minutes of your time, when they've used all 30 of theirs, if you're allowed to just continue playing, and moving your pieces as long as you have time left...that's a LOT of unanswerable damage at the end of a game. I know I could EASILY abuse that. Heck, if you're playing Boba BH, you could just get him into a shooting position, take his Twin Attack, say you touch activate everything else, and then have Boba attack again right away. That's like a 20 second process. So, at the very least, Boba would put out a ton of damage at the end of the game there, if not squeeze in a Disintegration or two along the way, most likely.
On the flip side, if the game automatically ends when one player reaches their 30 minute mark, that's just as easily abuseable, and could almost encourage slow play for some people.
So, something like the chess clock would definitely need some careful consideration.
I know at GenCon, slow play was a big deal, and after many discussions with people, it's definitely a subjective thing. What one person might think is slow play is not what someone else does. There was one game between my buddy James and Eric (Engineer) where Eric asked the judge to come over and keep an eye on things because he thought James was slow playing. Well, the problem was, it was a 200 point game, James was playing San Hill, and Eric had a WFF swarm (with like 16+ activations). So, their first round took almost 20 minutes. Well, on average, that was really not more than about 30 seconds per activation. But Eric called over the judge purely on the fact that the first round took so long. Was it slow-playing? Was it too long? It's so subjective. The crux of the matter is, if you're going to play a high-activation army, then you better be ready to play pretty quickly, otherwise, about 30 seconds per activation is pretty normal.
Even after all the different issues at GenCon, and after dealing with some slow-playing issues at my LGS, I am convinced that there is no change necessary to the rules system to deal with slow play. If someone is playing deliberately slow, it's blatantly obvious, and calling a judge over can address it. But as I've said many, MANY times in the past, learning to capitalize on someone else's desire to play slow is the best option. If you believe they are playing slow, then you already have an advantage, because you know that your opponent doubts their own strategic skill in being able to beat you. So, they are depending on their ability to manipulate the game. I've yet to play a squad that wasn't able to work around this. You simply play smart, and play quick. While they are taking their sweet time to determine their next move, you have already figured out what all their possible moves are, and your best responses to those. So when the opponent moves something, you immediately respond with your two activations (i'm talking like, 10 seconds for your whole phase sometimes). That REALLY unnerves them even more, it makes you look superbly confident, and makes them doubt their chances of winning even more. Then, all it takes is to get a small point lead, and let them slow-play as much as they want to. 90% of the time, they'll end up making really stupid mistakes at that point, because they then switch to rushing their moves to try and catch back up at the very end of the game. This is when you deal the really crippling blows and win the game anyways.
I've yet to lose a game and afterwards say "You were playing SO slow, and you cost me the game!" I might've said now and then "Oooh, if only we had time for one more round" but any time I've said that, I know that we played a good game, at a good pace, and it was my own fault for not getting the victory points fast enough.
So, in closing.....stop trying to fix the problem that other people have. Learn to overcome it.