Were it mine, I would do everything possible to flush the evaporator as best it could be flushed, THEN I would use a suction side filter. There are screens that you can get and other aftermarket products.
Don't take a chance with this, the stakes are too high. I recommend that you post a message for Tom on the www.ackits.com to see if he can recommend a suction side filter of some sort.
BTW the service advisor that told you that these filings would be trapped by the filter drier needs to take up another line of work. He obviously doesn't know what he's doing in his current position.