A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.
But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.
Here's what the 5" looks like on my mill.
I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.
Since one of the classes I teach is AutoCAD I get asked about this a lot. Yes after 3 years if you still have a valid school email you can upgrade too the newest version, I like to upgrade every year just to keep up to date with changes in the program.
One thing that is not too well known is this applies to all Autodesk products, I currently have Inventor on both my computer at work, and my system at home. But you can get copies of all of their products including Fusion, Revit(used in architectural drafting) 3DS(used in video games and movies) and everything else on their catalog.
Just remember that you need an educational email address, they do check up on this periodically and you don't want your program locked out in the middle of a big project.
That sounds great till you have to write it all into G&M code, that is one of the biggest advantages about using AutoCAD or solidworks, depending on what software suite you have some of them will write your programs for you like Catia will or you can dump your 3d model generated from solidworks or AutoCAD into something like surfcam and have that program write the code for you.