What are the difference in terms of chanting benefits between main version of panchdashi ? Shuddha, saubhagya (bala embedded), laghu shodashi, maha shodashi. ( i suppose there are ghuya n para also but extremely rare)
I can give you the MAhAtmya or greatness of various kinds of Shodashi Mantras. All references are from Tantras like Rudra YAmala, BrahmA YAmala, Sri Krama, GyAnArnava Tantra, YoginiTantram, Kuloddisha, Siddha YAmala etc etc as quoted in Brihat TantrasAra's Sri VidyA section (which is pp 322 onwards).
From GyAnarnava Tantram:
Vaktra kotisahasraistu jihvAkotisatairapi |
Varnitum naiva shakyeam shrividyA shodashAkshari ||
Vaikhari vAchyabhAvatvAdashagunavarnane |
Yato niraksharam vasatu parA tatraiva kAranam ||
MukibhutA hi pashyanti madhyamA madhyamA bhavet |
BrahmavidyAswarupA hi bhuktimuktiphalapradA ||
EkocchArena deveshi vAjapeyasya kotayah |
AswamedhasahasrAni prAdakshinambhuvastathA ||
KAshyAditirthayAtrAh syuh sArdhakotitrayAnvitAh |
Tulyam na yAnti deveshi nAtra kAryA vicharanA ||
EkocchArena girije kim purnabrahma kevalam |
ShodashArnA mahAvidyA na prakAsyA kadAchana ||
GopaniyA tvA bhadre swayoniriva pArvati |
[Lord Shiva says] Even if I had thousand crores of mouths or hundred crores of tongues, still I could not have described the greatness of this 16-lettered Sri VidyA... It is the BrahmavidyA and the giver of Bhukti and Mukti. Only one chant of this Mantra is equivalent in merit to crores of Vajapeya and thousands of Aswamedha Yajnas. The merit of circumambulation of the whole earth or that of visiting KAshi-like crores of Tirthas even can not match the merit that is obtained upon just one chant of the Mantra and etc.
- BijAvali Shodashi:
From Rudra YAmala:
ParA kAmancha vAgvijam mAyAm shribijameva cha |
VijAvali shodashiyam sarvatantreshu gopitA ||
RAjyam deyam shirodeyam na deyA vijashodashi ||
The VijAvali Shodashi is kept secret in all the Tantras. One can give the kingdom, even one's own head, but not the Vijashodashi.
From BrahmA YAmala:
Shodashiyam sugopyAhi snehAd devi prakAshitA |
AsyA mAhAtnyamtulam jihvAkotishatairapi |
Vaktum na shakyate devi kim punah panchabhirmukhaih |
Api priyatam deyam sutadAradhanAdikam |
RAjyam deyam shiro deyam na deyA shodashAkshari ||
This shodashi Mantra is extremely secret but still I revealed it due to your affection. It's greatness can not be described even if one had thousand tongues. How can I then describe the same with my five faces? One can give one's most beloved possession, son, wealth, wife, kingdom and even one's head but not the Shodashi.
ShrimahAshodashiyancha ya khyAta bhuvanatraye |
JyAnena mrityuhA vidyA sarvAmnAyainamaskritA ||
SaptalkshmA mahAvidyA tantrAdau kathitA priye |
SArAtsAratarAbhutA yA yA vidyAh sugopitAh ||
VahunA kimihottena tAsAm sArAtishodashi ||
This MahAshodashi Mantra is famous in the three worlds. One who knows it can defeat death. It is prostrated by all the Amnayas. O beloved, there are seven lakhs of MahAvidyAs being propounded in the Tantras. And the Shodashi is regarded as the ultimate essence of the most secret of all such VidyAs.
- SaubhAgya Mantra:
SaubhAgya Mantra is simply a variant of the Shodashi (It is a SAdi VidyA not KAdi). So all the above verses will apply to it too. Plus it is also said as the giver of good fortune (saubhAgyadayA) as the name itself suggests.
From Sri Krama:
SaubhAgyam kathayishyAmi srinusvaikamanAh priye | Shaktih swayambhuh shambhushcha shatrushcha bhuvaneshwari|| .. eshA tu pArameshAni sundari subhagodayA || ...
And, apart from all these Mantras, there are plenty of other variations of Shodashi, all given in the TantrasAra, which were worshipped during different times, by different deities. There are LopAmudrA and KAmarAja Bheda also.
There are SwapnAvati, Madhumati Mantras too which are formed by the Samputana method on the Shodashi.
There are the Pancha Sundari Mantras too viz- BhAshA, Srishti, Stithi, Samhriti and NirAkhyA. And, finally there is Dipani of Sri VidyA.
All these Mantras have similar chanting benefits and greatness.
Typically something like the verses given below:
BhogamokshapradA sAkshAt purushArthapradAyikA |
AnayA sAdrishi vidyA trailokye chAtidurlabhA ||
NAsti nasti punarnasti satyam satyam vadAmi te ||
[The Sri VidyA] is the giver of Bhoga and Moksha and giver of all the PurushArthas. A VidyA comparable to it is very rare to be found in the three worlds. [Such VidyAs] don't exist, don't exist, don't exist- I am telling the truth, I'm telling the truth.
Also, I am not sure, by Laghu and ParA Shodashis, you're referring to which particular variants of the Shodashi. Because I haven't found anything like those in Nityotsava, Brihat Tantra SAra or even in NityoshodashikArnva Tantram. So, can't update regarding those Mantras.