there is a guy that sells dillon stuff, that cuts thru all the crap and just sells you what you need and what you want.
the name of the web site will come to me, give me a few.
If all you want to do is load pistol ammo, the square deal from dillon is a very good deal. you just must use dillon dies.
edit found it
http://www.brianenos.com/index.html
Bought my 650 setup from Brian.
Good guy to work with. Let him know just what you need and he will "custom" fill your order...making sure you have all the options you need and none you don't need.
Sometimes you might not get a part that would come standard with an order from Dillon but you don't pay for it either.
You might have to then purchase the part if you expand your capabilities, however.
The 650 has room for 5 dies in the tool head where the 550 and Square Deal only have 4, allowing for more options.
The primer system on the 650 can be removed with with only two hex screws and you can have a large primer system and a small one on hand and swap out as needed.
The "Quick Change" packages save a lot of time but cost a lot of money. They consist of a tool head loaded with the dies of the caliber, including the powder/expander die and a powder measure. You will still need to swap the shell plate.
If you have the case feeder, you may have parts to change there, the biggest time consumer being the case feed plate. However .40 S&W and .45 ACP use the same plate and 9mm and .380 ACP use the same plate. It is not fun to change the plate. You either need a step ladder (or chair) or need to remove the case feeder from the machine. I use a 3 step ladder.
Then you have to consider power charge. You can have the powder measure on the quick change tool head set for one powder and load and can either have another tool head with powder measure set to each of your loads, which gets expensive.
An option I use is to purchase a micrometer adjustment kit from UniqueTek
http://www.uniquetek.com/site/696296/product/T1231An easy installation but with some fine fitting to get it set correctly.
Unique offers several items for Dillon presses. One is the CNC machined tool head and another is the Toolhead Clamp Kit.
Don't know if the increased precision advertised for these products would make a real difference...but I'll give it a try some day.
Of interest to reloaders would be the Brass Wizard. Anything that makes brass recovery easier and quicker is golden.
http://www.uniquetek.com/site/696296/product/T1231