I can't really comment on mini mills because I've never used one.
I would like to point out though- Especially with the mill and surface grinder, you'll find ALOT, worth repeating... ALOT of uses for these items that you haven't even thought of yet. Making guards is the very tip of the iceberg for these machines capabilities.
Keep the "big picture" in mind. I can see myself in the future totally spending some serious bucks for a knee mill with DRO and quite possible auto feed on the table and retiring my mill/drill to "really AWESOME drill press" status. It'll be a long time in the future, lol but I could justify that purchase easily even with pricetag of probably $7000.
Purchasing my mill was a target of oppertunity but I was saving for a dovetail column mill at the time and for $400 I couldn't pass up the deal. In retrospect, I use the mill enough that passing on the "deal" and continuing to save for the dovetail machine would've been a wiser move.
Since getting the mill a hardly ever use my drill press.
Another thing I always keep in the back of my mind with big knifemaking tool purchases- I could probably sell my mill or surface grinder in a heartbeat if I had the need and cash to upgrade. This fact makes the purchase of a "starter" machine far more bearable
Like Ed said, get a machine that takes R8 tooling so if you want to upgrade later you'll be set with the tooling you have.
Tool purchases are always difficult decisions. After owning a mill for awhile now I'd skip the mini in favor of something larger and more rigid. I can't ever remember someone saying "I've got this Bridgeport... but wish I had a mini mill" LOL
Good luck -Josh