Thank you very much.  I need to cogitate on this a bit.  Alternative 1, Option 1 seems viable at the moment.  I will let you know.  The need for Reorganization demenishes with more liberal and thoughtful key words.

Thanks for responding so quickly.

1. Firt of all, I don't have any experience with Tresorit.

That's ok.  After all, I am a researcher.  Tresorit claims to have a level of security that some of my clients want. Besides that, much of this is outside of your domain as I perceive it.

2. Since you are using a Mac desktop, Mac laptop, and maybe a iPad, I wonder why you made no mention of using Apple's iCloud.  Although iCloud has its flaws, the seamless integration with Apple's apps is really nice if you're an all-Apple person. 

For some time I have been moving out of Apple apps to those more suitable for my work, ie the LibreOffice suite, mind mapping, etc.

3. And, due to the extreme security in iOS, iCloud is the only way you can access Safari bookmarks on that iPad.

I didn't know that.  Maybe I will have to stay with laptops.

4. Do you use any web browsers other than Safari?

Not now but I am open to others.

5. How do you "tag" bookmarks?  In BookMacster?

Yes.  It's very convenient and I also organize out of BookMacster.  I love it.  I do want this on both platforms.

6. Do you currently have BookMacster installed on both Macs?  If so, is your .bmco document file in a Dropbox folder?

Not yet because I have been using the laptop for prepared presentations only.  A new phase of my teaching requires the use of web pages in my presentations on site, hence BookMacster on the MacBook Air.  I have only a few bookmarks on the laptop.

7. When you bookmark websites, do you do so by adding directly to BookMacster through its Anywhere Menu, Dock menu or Menu Extra?  Or do you add to Safari's internal bookmarks?

I add bookmarks with Safari and let BookMacster sync things up.  Often I reorganize them around new projects and that is why I am tagging more and filing less.  There is a lot of crossreferencing involved.

In short, I must be more alert to accelerating paradigm shifts in my work.  This involves a level of planning that I am only now adjusting to.  It requires opening new doors and shedding old baggage.

I am a researcher, arthur and teacher. 
I am an applications user - not a computer geek.
99% of my work is done on a Mac desktop.
I use Safari for browsing, duckduckgo for my search engine and Dropbox sparingly for file sharing and cloud storage.  All are up for review, especially Dropbox /Google.
I use a Mac laptop for presentations, files, etc.  on a tv in the classroom or other venues.
I do not want everything that is on my desktop available to my laptop.
I sometimes add websites to my bookmarks from my laptop.
I want my bookmarks synchronized between desktop and the laptop.
I sometimes organize bookmarks by file but I find myself increasingly using tags.
I sometimes add notes from my laptop.
I read eBooks and Kindle on my laptop.
I also use VMware Fusion for a few important Windows applications (no Microsoft) but I keep all of the files and bookmarks in a Windows folder on the Mac.  No WIndows apps or email ever.
I weekly do a bootable backup of everything.

What I want in the light of the above, is good file, backup and bookmark synergy considering my use of these marvelous devices. I may add an iPad.

BookMacster is not up for review.  It has been very helpful

My immediate questions:
1. 'In the light of the above', Do you have a tested alternative to Dropbox/Google for syncing between computers and cloud storage?  Do you have any experience with Tresorit SOLO?
2. Would you consider outlining a transition?

I will be grateful for your help.  Your help can save me many hours of plodding through swamps where I have little competence.  I need the time for works for which I am commissioned.