D'Addario shows those strings as having almost 3 times the tension as the originals, but that's when they're strung on a 34" scale bass.
Did they make any noticeable difference in your neck relief?
If I wake up one day and I have a pile of wood instead of a working bass, I will report that here.
I hope and have a reasonable expectation that it won't be the case.
You can calculate the tension of a string for a specific scale - pitch being equal and provided you know the string's tension at another, given scale - by multiplying the known tension value by the ratio of scale lengths squared.
[597mm is the scale length of the Taylor, and the one which D'Addario used to calculate the tensions they provide for the phosphor bronze nylon-core [This invalid link has been removed] set; 628mm is the scale of the Ibanez PNB14E; 863.6mm is bass guitar standard (long) scale, which all L-S bass set tensions provided by D'Addario are measured at, including the
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(628/597=1.0519262981574539363484087102178)^2=1.1065489367552446767618101675322
Multiplying the EXPPBB190GS tensions by the above ratio, and rounding the results somewhat, we get
G 12.172lbs
D 14.263lbs
A 13.146lbs
E 15.923lbs
=55.504lbs total. These are the tensions of the Ibanez PNB14E basslet in its stock stringage.
(628/863.6=0.72718851320055581287633163501621)^2=0.52880313373083493571831434320308
Doing the same operation to the EXP220 tension values, we convert them to the target 24.724" scale of the Ibby:
G 17.821lbs
D 22.686lbs
A 20.095lbs
E 18.191lbs
=78.863lbs total. This is how much the nickel-plated set pulls on the Ibanez.
The increase is significant, but still less than 50% (the nickel-on-steel E in particular is not all that tighter than the nylon-core it replaced).
More importantly, the total tension of the set is what you'd get by putting a .009-.042 electric guitar set on a 3/4 guitar. Wet noodles, that is.
Is it quite a bit more than the stock set? Well, yeah, 23-odd pounds more. Is the instrument so underglued, underbraced, underwooden, underrodded that it will fold under that tension?
I believe a large factor involved with getting decent volume out of these small instruments is a thin top! Compare a 34" scale ABG to one of these micro acoustic basses. Big difference in terms of structural rigidity. I bet that's where the move towards lower tension comes from. The issue isn't the neck warping, but the top (soundboard) deflecting.
I agree that the neck will be fine since it has a truss rod, and the thing to watch for is the bridge and the top area around it. (The Ibby may be a little more robust than the Aquila ShortBassONE, hopefully.)
However, in my opinion the main reason why this new class of instruments comes with nylon-core strings is that they're flexible and less prone to inharmonicity at the relevant scale than steel-cores, while being in the same general ballpark tone-wise and not terribly quieter; the ukulele-bass market, OTOH, has proven that a number of players were willing to compromise on playing feel (read as: give up on the tension they were used to) for portability (and part of them, those that buy Pyramid and Kala roundwounds, were not necessarily after double-bassy tones).
JMO.