Bob,
You'll be fine with the 5215!
I gave up trying to argue against the myths...but, fact is you will see little, to no, difference at all between these two antennas.....(see #2, below for details as to "why" some will need to choose one or the other...but for most, it's a non-issue!)
1) If you look at my earlier postings here in this thread, you'll see that "a half-wave antenna" is a "half-wave antenna"!!
And, no matter what the layperson sailor grapevine says, the 5215 is NOT a "loaded" antenna, but a full half-wave vertical....the "coil" is just part of the tuned impedance matching
network, allowing you to feed the antenna directly with 50-ohm coax (NOT a "loading coil"), just like the bottom one foot of the 5400 is the "decoupling"/"matching" section (allowing you to directly feed the 5400 antenna with 50-ohm coax)...
I know that many will tell you a 1/2-wave dipole antenna is "better" than a 1/2-wave, end fed antenna...and in some special cases, this is true...BUT...
But, in our applications, it is not true!
(and when comparing well-designed and built antennas, such as these Shakespeare's....there is NO truth at all to that myth!)
2) But, having said all the above....if you need an flexible antenna to get under 65' bridges, etc....then you WILL choose a 3' SS whip (1/2-wave end-fed antenna)...like the 5215...
And, if you must have a rigid antenna (if you have extreme winds and no bridge clearance issues), then the 5400 is a good choice....
BUT...
But, understand that there will be little to no difference in their performance....
The raves that most VHF marine antennas get, are almost always due to it being "new", with clean (and/or new) connections, and many times new coaxial cable as well....(and sometimes 'cause their old antenna was crap!
I hope this helps!
Fair winds....
John