I'm always mixing small batches of concrete for various projects on our 25 acres. I used to mix next to the barn where I store the materials, and carry the wet concrete to the site in the FEL bucket. It was always a pain to clean, and pouring the mix from a 6" wide bucket into a small form wasn't always possible. In some situations, it usually meant shoveling by hand. I also found carrying wet concrete in a FEL bucket can make the tractor unstable on rough ground, since the concrete tends to "slosh" from side to side.
I thought about investing in a FEL mounted SSQA or PTO mixer but the price was prohibitive for the small projects I do. Instead, I picked up an old stand mixer with a burned out motor at a yard sale for $50. I welded a blank SSQA plate to the mixer legs and replaced the bad electric motor with a hydraulic model, which I power via the tractors 3rd function valve. The whole project cost less than $200.
I now load the ingredients at the barn and mix the concrete while transporting it to the job site. I use the FEL to pour the concrete from the mixer precisely where I want it in the form. The only time I get off the tractor is to reload the mixer.