Despite such limitations, it does continue to get easier to obtain many records digitally. Most researchers start with Ancestry.com, but familysearch.org offers a surprising number of digital records all for free. Coupled with that is the ability to contact the Family History Library and request copies of specific records that are listed, but not available digitally on line. I frequently do research for others and have often been able to obtain records in this manner where I would once have had to order the film, a more time consuming and costly method.
I recently was doing some work for a client who was trying to verify a great-great grandmother's name and the town they came from in Bohemia. I always begin my search with census records and build a database, then I use that information to calculate the year of birth, marriage and immigration. Often these vary in different census years, but it begins to define a range and some data points against which to cross-check potential records. Census records are also useful when they have in-laws living with them. A mother-in-law listing can reveal an unknown maiden name or conversely the married name of a daughter.
After building this database, I began to search on individuals. I don't just search on one name. I search on all of them as some may offer little information while other may be more generous. In this case the mother's name was only listed on one child's death record. I ordered it and several other vital records from the Family History Library and had digital copies within a few weeks.
Referencing the dates provided in the census, I limit the immigration period and begin to search immigration records, usually making use of the enhanced search functionality offered by stevemorse.org. In this case I had several records that were close, but one which matched on birth and immigration dates. It also listed the town of origin.
If you know how to leapfrog from one source to another you can often solve the puzzle fairly quickly.
And speaking of changes....Anyone involved with genealogy has had to consider the fact that borders are often quite fluid, far more so than we often think. Poland in particular, the early home to many Jews, had extremely flexible boundaries which was also reflected in the changing language of civil documents. Russia's current day grab of the Crimea echoes Germany's grab of the Sudetenland region of Czechoslovakia which was populated by ethnic Germans. Now of course Czechoslovakia is yet another change as it became the Czech Republic and Slovakia.
A link is floating around that covers 1000 years of European border changes and is quite fascinating. I was particularly shocked to see the amount of territory held by Germany during WWII. There is something about watching the map change that is particularly jarring.
Note: I've since learned that the time lapse map is from Centennia Historical Atlas software. The software tells you what historical events were occurring as borders changed.
And the word is that NY probate records are just restricted after 2009 although death certificates in earlier files may no longer be available.