I've put 3 hours in to the Beta now and just thought I'd post some observations/discussion points. Not all are medic specific but some are.

• Stop moving to shoot further than your immediate vicinity. Movement screws up your aim even more so than it did in KF1.
• The medic shotgun is great, but it chews through ammo. Make sure you have a second weapon. I usually use the medic pistol till wave 4, then either the Assault Rifle/SMG until wave 7.
• Medic Grenades are godlike. Stick them in a cluster of people and you'll be a great asset to the team. If there is a clump of enemies, or the boss is stun locked, the medic grenades can really chew through their health.
• Semi-Auto is your friend! The Varmit Rifle, SA-80 and SCAR have semi-auto modes that make you much more accurate over range!
• At the start of a game roam the map! There aren't so many enemies that you need to stick to a group and you can usually pick up a varmit rifle, pump shotgun or katana to use for wave 2 or sell for some cash
• You don't have to stick to the weapons of your class. Using commando assault rifles or support shotguns will level up those perks, even if you aren't using them. If you're a medic and need to heal quickly you can just switch to your medic pistol for quick long range assistance.

I'm really enjoying the beta so far and have played some great games with strangers and friends alike, props to Tripwire for a great Beta and building a great community!