Read the description of the Mini 2.1 carefully. It might get you through a WORK day (8 hours). OTOH, the Reo Grand's 6 ml bottle and 2000 mAH 18650 battery last me from wake-up to bedtime. I carry a backup eGo with cartomizer in my computer bag, but that's it. The Mini 2.1, as pointed out, only has half the juice and battery capacities.
I did buy the repair kit, but I'm a "be prepared" kind of person. If you don't get it, at least get a spring. You don't need a safety fuse, especially with the ceramic base RM2. I think they over-compress the spring.
Get a couple of spare o-rings and a couple of spare post screws for the Reomizer 2. As said above, the RM2 is dead simple to coil and wick. If you get one, Rob has samples of 28 AWG Kanthal. He also has 2.5 mm silica wick, but you may want to stick with wicks made from cotton balls.
You'll need batteries. Stick with the recommended AW IMR batteries (2000 mAH for the Grand). I rotate three, but don't carry a spare to work. NEVER just put a battery in your pocket or purse! Get a plastic case that holds two batteries. Wait, get TWO, so you can have one for each spare battery with a bottle of juice and some cotton in each. That's my long weekend setup. I got the batteries and cases from ProVape.
This is the battery charger I use. They make a four cell version, but I have limited space on my end table. This charger can also operate off vehicle/boat 12VDC power (you'll need a cord), so you can charge your batteries from your vehicle in the event of a power outage.
Hope this helps.