Yes, you can pick up the nuances through milk. Depending on the lever you have though your shot draw might be smaller, i.e. Ponte Vecchio, Elektra, Olympia, etc., so your entire drink would have to shrink or you would have to put more shots into it. There is definitely a learning curve and experience is really the only thing to counter it. I am sure you would eventually get the hang of it, but with one double a day, as Peter said, it would most likely take quite a while to get great at pulling shots on one.
Do you want to buy the lever new or used? I would push you heavily toward used. The only electronic parts in a Lever machine are the heating element and the pstat. As far as working on machines goes they are very easy to work on, fix and maintain. If you peruse craigslist / ebay enough you will run into an elektra or ponte vecchio, even an occasional commercial lever for $500 or less.