Gurfateh
Well Das can say a few things.
Nirmalas or Taksalis or Nihungs are not catholics but Orthodox
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=5594
Catholics are more like AKJ
And protestants are refomers like Sirdar Sahib Kala Afghana.
Das was initial against the solar calender as in past both Solar(Nanak Shahi with Sankrands and Vaishakhi) And Luner Calneder(Vikrami) were used.
But due to articles in Panchjanya of RSS opposing NanakShahi Calnedr by S. Purewal made Das support the NanakShahi Calender in Present as who on erath were RSS people to interfere in our internal affairs.
So far in SGPC and thier things in mainstreeam Das support the Soler Calnedr of Nanak Shahi which is recently introdued.
Coming on the points of respected Sant Samaj.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=5594
Well they are much more better preachers then our protestant Sikhs.
Guru Maharaj Used the festivals of Holi,Devali and even Dushera to wean away Hindus from idolatory and to preach Sikhism to them.
Later on Mahants may even have made used of Kartik Purnimah to be used as Gurpurab of First Master to let Hindu do not go to Brahmins and be our Part.
In fact most of the history writtan in old texts talks about Vikrami Era or Calender and dates are based upon it.
Yet Sikhs do not have to rely upon Barhimins for Alamanac as Mahants have thier own command on that.
With Nanak Shahi Calander Missionaiers have also dislodge the Sants from this field.
What Das knows about Sikhsim day is not at all important to us like Grah Natckshtras or Zodiac etc or Rashi or Palentory positions and events on Gurparbs are morte to inspire us be it on that day or after 100 days from that day.Punya or Mahttam(Gaining of virtue in heavan) due to doing something at one particular day is to be found in Islam or Hinduism but is Anti Sikhism.
Needless to say that Saka and Vikrarmi Calenders as per Indian Govt are also been made soler and scintific and as it happens in Iran that Hizri the Islamic one and the Kursheed or solor one of that Countary both are used.
So das can recomned that if someone wants to use old calneder we must not feel Bad but yet Nanak Shahi Calender is something welcoming yet Hola Mahla or Bandi Choor Divas etc and local customs of Sants need to be respected.