The precise answer is the learner may chose whichever is easily understandable to him.
If he wants to know पद and पदार्थ separately so as to identify the विभक्ति and other sentence factors, he can chose the split reading.
It is common sense that if he wants to read or recite as a श्लोक in different meters, melodiously and fluently without break, he can chose the "sandhi" version. Try yourself, whichever is convenient for your purpose.
Technically, "श्लोकपादः पदम्" and within the पद as a single unit for recitation, the rule was formed. Otherwise, even if it be a श्लोक, it is also after all a वाक्य, and becomes under the category of
संहितैकपदे नित्या नित्या धातूपसर्गयोः ।
नित्या समासे वाक्ये तु सा विवक्षामपेक्षते ॥
which is based on practical grounds and if सन्धि is opted, it is obligatory that it should follow the सन्धि rules as also while splitting.
Otherwise Panini doesn't say anything, about it. All his rules, apply
"संहितायाम्" if "sandhi" of संहिता is opted, i.e. to be pronounced fluently without gap and all the rules follow then only.
The answer depends on the purpose of the learner and his standard. If he can automatically identify and relate the parts into a complete sentence without changing the order (which is also not mandatory for understanding the श्लोक). The other way is, if he only wants to recite it as a मन्त्र without bothering about their meaning, then also he can use the सन्धि form keeping the tune of अनुष्टुप् or any other metrical composition only by listening. Like the recitation of the वेद-s and even घणपाठि-s need not necessarily know the meaning, but only by recitation split or संहिता, and repeating in the prescribed order, they could be घनपाठिन्-s, unless they themselves want to know the meaning as per the commentaries or otherwise.
The same applies here also. If one wants to know the meaning, one can read the commentaries or the split version of the श्लोक and if he wants to recite it metrically, it is convenient to do so if in संहिता form. In short, there is no question of correctness of one or the other version.
--
Dr. Hari Narayana Bhat B.R. M.A., Ph.D.,
Research Scholar,
Ecole française d'Extrême-OrientCentre de Pondichéry
16 & 19, Rue Dumas
Pondichéry - 605 001