I started using 750words for my writing in early 2010. Despite having had a streak of over 200 days and having written over 700,000 words using the site, though, I can't say I've used it regularly in quite some time.
The owner of the site has made the difficult decision to switch the site over to a pay model starting next month. This caught me off-guard since it's directly opposed to what he's always said up to this point, but I understand that situations change. For me, then, the question is whether the tool is worth it for me.
It's really no different from magic, is it? I shy away from using wands and amulets and all the magical trappings, but I have my forging equipment, and I still consider that magical. It's how you use it, not what you use, that matters.
I prefer to go without fancy tools, for the most part. I don't like getting hung up on what I'm using instead of what I'm doing. 750words is a great site, but it's a tool. I should use it as long as it's useful, and let it go when it no longer is.