The levelwind will cut your cast down slightly - not enough to be concerned about. If you maintain the reel and clean and oil the worm and paul frequently it will not be a problem.
If you intend to fish the reel with plugs, you almost have to have a levelwind. I am more interested in watching my plug and the proper action, than having to be sure the line is being laid down properly with my thumb. Also if you fish at night ( and we all do ) a levelwind is a must. With a baitcaster the line has to be laid down on the spool properly or the next cast will result in a backlash and possibly a plug or jig ending up in Europe. If this is your first baitcaster, you will be much happpier with the levelwind and the magged reel. Buy the Abu, you will not be sorry.
I do not know where you buy your stuff, but i would recommend that you deal with M&D bait in Wareham. Mike is a knowledgable guy and will help you out with the reel and also change the drag before you start. Saltwater edge is another shop that will help you - just depends on where you are located. Buy the reel from a baitshop and you will get the service you need.
:spidey