Wander where you read about the 0.5 Qts not suitable for TL!!??
Especially, ML-TQWT´s are extremely well suited for JBL´s Qts values between 0.35-0.55
The type LE8T speaker is a full range speaker, but if not using a properly designed BSC filter its frequency response could be dominating in the mid freq. region and thats why you must use the BSC filter for to correct for speaker frequency response, baffles, and for room acoustics
If need be (your choice) you could use a small JBL "ti" dome tweeter for the UHF (crossed at > 12 kHz ca).
Regarding your amp´s output power capability: I feel the the 25 watts total power is far to small for to receive good, high output in the VLF regions. This speaker can withstand at least 50W of power (25 Watts RMS) and if trying to get high bass output with only 25 Watts at hands you will very soon reach the clipping level in the peaks/dynamics resulting in distorted heights and bass response.
You could also damage the speaker due to it is not built for clipped/distorted audio signals.
For to receive good sound reproduction from this speaker you will need a one that is capable of at least 50-75watts of clean power outputs for to make this speaker sense and if using a well design BSC filter, some of the power will be lost in this filter resulting in even less power to the speaker than what your amp is pumping out.
Myself uses a bridged NAD for those speaker (@ 90 Watts maximum outputs) and I feel it is amazing how much sound this small speaker is capable to re-create/produce, from 30 Hz to beyond 15 kHz.
Regards