Pretty much yes.
There could be adventures along the way, but I think this outcome would position you well for the future.
The biggest question is how old is your HBOOT.
There is no S-OFF for 1.57 and existing exploits for 1.56 don't always work.
If you can get S-OFF, you can do anything, including a) destroying your phone by mistake; b) changing your mind later and going back to S-ON; and, my personal favorite, c) destroying your phone in the act of trying to go back to S-ON (due to modified/ damaged HBOOT partition).
If you can't get S-ON, well, see if you can get back to stock.
Occasionally you are truly stuck and can neither go forward nor backward.
Which in your case is not so bad. 4.3 works great. Honestly plenty of people here are trying to go *back* to 4.3 after trying 4.4.
With S-OFF you can always do that. S-ON, not so much..
Sent from my HTC One using xda app-developers app