According to my lawyer who I hired for my case (much different case not involving drugs) winning in trial is always less then 50% chance. Which I found confusing cause the guy wins over 70% of his cases and is one of the top lawyers in my state. One of the reasons being is that if you're in the defendants seat, the jury already knows you did something wrong otherwise you wouldn't be there. In my case I was charged for the crime i didn't do and wasnt charged for the crime I did do (broke a lamp in a hotel). I was charged with a serious offense but as it unfolded the accusser had a few loose screws and a lengthy criminal record. The point is a GOOD criminal lawyer doesn't neccersirily wants to take a case to trial if he knows he will loose, he should be upront about it.
One thing that suprises me is that you say that 15k option is the expensive one when a good criminal lawyer doesn't usually charge under 300$ an hour. With few days in trial and preperation for trial should amount to over 15k usually.
With that said, a good lawyer should be able to find all faults in the case(as none are the same) and tell you aproximate outcome in trial but he will not be able to tell you an exact outcome. You should have a feel for which charges he thinks he will be fairly certain to get reduced or dismissed and which might stick. At the end of the day, trial is a gamble.
P.s also my case never had intent. So the whole thing crumbled up on prosecutors as the case went along.
Also in your case, there's no denial that the guy was caught with the drugs so the lawyer needs to find everything else possible to try to build up a good defense. That's something that only he would be able to advise you on though.

