xls to xlsm conversion: Necessary, beneficial, harmful, or broadly neutral?

[1eyedjack]

Hi

I have a number of .xls workbooks (with VBA macros) that were created in (and used in) Excel 2003, and worked fine for that purpose.
My office is converting to Excel 2013, a product with which I have no familiarity, so please bear with me.
This is a very general query, possibly too general to get an intelligent response. It may well be that each individual case should be considered on its own merits, but here goes:

My question is: Is it generally a good idea to leave the existing .xls workbooks in .xls format?
From my brief experience of the last couple of days my observations are:
1) Excel 2013 is FOR MOST CASES perfectly capable of opening and working with files in .xls format, and re-saving in that format (some of the cell formats such as background colour pallettes may get changed a bit).
2) If the existing spreadsheets did not require the additional functionality afforded by Excel 2013 (ie additional columns and rows), then it is a case of "if it ain't broke, don't fix it".
3) There are some rare cases where Excel 2013 does not like .xls files that were perfectly happy in Excel 2003 (an example I saw recently was conditional formatting by formula using Offset() in a moderately complex manner, which I posted here a few days ago). But in those cases having corrected these errors it is still quite happy with the .xls format.

So I guess that my original question might be subdivided into two:
A) Are there some invisible benefits to converting to .xlsm that I currently lack the imagination to envisage?
B) Am I storing up a world of hurt for myself if I (a) convert all my files to .xlsm or (b) not convert them, having run preliminary tests to eliminate any obvious errors in .xls files opened in 2013?

An example mentioned in another thread is that in some of my .xls workbooks I have defined names "Ref1" and "Ref2". The expanded columns in xlsm files mean that these names are now cell references. If there are other more widespread problems of this OR SIMILAR nature that I am likely to encounter then perhaps it would be best to leave them as .xls files. My greatest concern, however, is NOT that error messages are generated in these cases. I can correct for error messages. My concern is that an error message might NOT be generated but the behaviour of the spreadsheet changes.

[ragulduy]

I would suggest the time saved in converting the workbooks everytime you open them make it worth moving everything into .xlsm format.

[1eyedjack]

Hi ragulduy

Thank you for your response. Forgive me, please, but I did not really understand it. An alternative being suggested is that I do NOT convert the workbooks every time that I open them, but rather to leave them as .xls files throughout their lifetime of being used in Excel 2013.
That being the case, I am not expecting to spend any time converting the workbooks "every time [I] open them", where no conversion is taking place.
Am I missing something?

[AndyLitch]

.XLS files will open slightly slower because of the internal conversion and you'll see on the top bar that Excel is working in format conversion mode.
If they work ok and cause no noticeable delay and you have lots and lots of these files - I would stick to XLS..

[ragulduy]

Maybe I am confused in that case, I was under the impression that 2013 would convert an .xls workbook upon opening it. I guess that must only be in the reverse...

[Andy Pope]

If the workbooks are in effect read-only then I would leave as xls.

If they can be updated in anyway by the user I would convert them.

If they can be updated and you don't convert then changes made could present the user with the Compatibility dialog.
Simple stuff like colouring cells with the new theme colours rather than with colours that map directly to the old palette will cause issue.
And obviously any new feature will cause problems.

[1eyedjack]

Many thanks all.

They can be "updated" but I have locked them down to the point where the only updating done by other users is tightly controlled by macros, and then limited to simple data input (text and numbers).

I will flag the thread as solved by now. This is about as much help as I could expect given the vagueness of the OP, and much grateful. Rep to all