Medium and large format is wonderful to work with. I used a bit of 135 film when I was a teenager, and then crop and full frame digital as an adult, but I can't really see a good reason for using 135 film for any of my work. - I might pick up a Canon EOS system at some point for birding, but at the same time I might as well use my digital gear for that anyway.
But I do find a delightful irony in large format for me currently, which seems to keep me working with 120 film for the most part: I don't feel like I have the experience to do justice to a 4x5 negative to warrant the price, but at the same time I don't feel like I'm gaining enough experience from how I'm using my medium format to apply much to my large format work...
However, medium format is enough fun that I'm not sure I'll worry too much about the 4x5 sitting on the shelf for most of the year. [It is also a 'happy medium' medium... Large enough to do interesting work with, but just small enough that all my cameras offer some option that is reasonable to carry no matter what I'm doing: Day to day a TLR tends to ride in my messenger bag wherever I go, and a dumb folder gets stuffed in a pocket for days where the larger cameras get deemed 'too much to bother with'. My Pressman doesn't seem quite as portable...]
For double loading 120 on 220 reels [At least with the plastic Paterson style reels], I like to use the bit of tape that held the film to the backing paper from both rolls to reinforce the connection.
I had seen a suggestion to make a small split in the middle of both ends so that they form taps you can slot the film together in, but that just sounded like trouble. And I figure that the less fiddling with scissors I do in the dark, the better.
Taping a single side once resulted in the tape letting go on me mid-spooling, and overlapped a handful of frames to spoil development of the end of either roll.
For anything that I deem highly important, I no longer bother with the risk of double-loading, and will spend a bit extra on chemistry and my time.
Plastic reels, who messes with that?
I do, mostly because it is what my Paterson tank initially came with, and they work just fine as long as I use them correctly.
If it isn't actually broken, why spend money to fix it? I've since bought more plastic reels simply because they work just fine for me, and I rather not start on a mishmash collection with different quirks to learn.