Yes Roger, your eggshell method is a tried- and- true-way to separate eggs that I've used successfully for years when separating eggs, except when I've gotten a little of the yolk into the whites with bad results. Generations have done the same...until the time that I needed more yolks than whites for a number of recipes (or vice versa).
The yolk "sucker" is more efficient, more fun, and it usually aids in the removal of the chalise in the whites as well, which one might find helpful, not to mention that it is quicker. Depends on how many eggs you generally separate. If one separates eggs only occasionally, it might not be economical but it still might be fun for gadget lovers. As you mentioned, egg shells are handy for fishing out bits of stray egg yolk that were inadvertently broken into the whites, but if one needs to beat only the whites it might be tricky to occasionally completely fish out all of the yolk to successfully beat the whites into an egg white foam. No need for that concern when using this gadget. It is definitely not a gadget that everyone would use as much as I do, but some might be interested.
Roger, I'm glad to have your approach to egg separation and many others will be grateful for your method. Thank you for posting it. This little gadget has surfaced in my email in the last few days. Hopefully I've put a few pros and cons out there for consideration. I hope I don't sound argumentative or confrontational and just hope to put different views on it.
Rita