I've been evaluating Scalix ActiveSync for a few months and I have noticed massive issues with contacts sync.
1 user with Verizon "HTC Droid Incredible by HTC" has a problem of too many contacts, they keep multiplying currently at 18,000 contacts, started at maybe 300 contacts and they just keep multiplying like rabbits.
Another user I have more direct contact with we have tried many phones, all of them get too little contacts:
* Sony Ericsson Experia X10: too little contacts
* Samsung Galaxy S (AT&T version IIRC): too little contacts
In both of these cases it seems the same contacts never sync to the phone.
Both of these users had Windows Mobile 6.5 without any issues. User #2 we also setup an iPhone 2G and that syncs fine. I use an iPhone 4 and also that works fine.
I don't understand how this is possible if scalix has allegedlley has "official license" for ActiveSync protocol.