As far as other sects liking Shugden, I am quite interested in this, because I have both Kagyu and Shugden tendencies myself. From this site, I found the following:
Dear Blueuapli,
The great King Dorje Shugden has in fact been prominent in more than just the Gulug lineage and has appeared in various instances in the Nyingma, Kagyu (Drukpa Kagyu) and Sakya lineages.
First, it is well known that the Nyingmas can trace the origins of their lineage to the great Indian Master, Padmasambhava (Guru Rinpoche) and one very visible evidence that the Nyingmas did propitiate Dorje Shugden can be seen in this antique thangka depicting Dorje Shugden surrounded by the Protectors and Yidams of the Nyingma lineage, with Padmasanbhava above Dorje Shugden. Note: Please watch by clicking on the dorjeshugdem.com video server link:
http://www.dorjeshugden.com/videos/miscellaneous/thangka-of-guru-rinpoche-above-dorje-shugden/Dorje Shugden was also prominent in the Sakya tradition and in fact one of the past incarnations of Dorje Shugden was as Sakya Pandita, the head of the Sakyas. It is also believed that initially the spirit of Tulku Drakpa Gyaltsen, driven by his Sakya imprints travlled to the Sakyas whereupon Dagchen Dorje Chang Sonam Rinchen, who was the head of the Sakyas at the time recognised Dorje Shugden clearly and enthroned him as a Dharma Protector. Sakya praises of Dorje Shugden was later composed by the Sakya Master, Kunkhyen Ngawang Kungo Lodroe.
In fact in many accounts, Dorje Shugden was first worshipped by the Sakyas as a Dharma Protector and was inducted into the Sakya pantheon of protectors and together with the other Sakya deities, Dorje Setrab and Tsi’u Marpo, were known as Gyalpo Sum, or The Three Kings who were widely revered within the lineage.
In yet another account, Dorje Shugden was reincarnated directly into the line of the Sakya throneholders itself:
http://www.dorjeshugden.com/great-masters/enlightened-lamas-series/dragshul-trinley-rinchen-1871-1935-the-39th-sakya-trizin/Regardless of variations to the history of Dorje Shugden in the Sakya lineage, there is no doubt that the protector was very prominent in the lineage in the past.
As for the Drukpa Kagyus, reference to Dorje Shugden is via the great writings by one of the very significant figures in the Drukpa Kagyu sect, Jigme Norbu who was recognized as the mind emanation of Zhabdrung Ngawang Namgyal who held the honour for being reinstating the independence of Bhutan from Tibet.
Amongst Jigme Norbu’s collection of great works published as The Collected Works of the Fourth Zhabdrung Tulku of Bhutan were writings on rituals and invocations to the Drukpa Kagyu’s pantheon of protectors including Mahakala, Tsering Chenga, Shinkongma, Rahula, Pam Busum, Tsiu Marpo, Palden Lhamo, Chatri Tsengod, Dorje Shugden, and Jagpa Melen.
More recently, the 16th Karmapa H.H. Rangjung Rigpe Dorje was well known to have advised that there will come a time when all will have to depend on Dorje Shugden.
Therefore up until recent times the other lineages other than the Gelugpas, were proven to also have propitiated Dorje Shugden. This may have changed due to political pressure from the powers that be, or due to the jealousy of the other sects of the supremacy on the Gelugs.
Hope this helps.
Further important readings on the subject:
http://www.dorjeshugden.com/great-masters/enlightened-lamas-series/jigme-norbu-1831-1861-the-fourth-zhabdrung-mind-incarnation/http://www.dorjeshugden.com/great-masters/enlightened-lamas-series/dragshul-trinley-rinchen-1871-1935-the-39th-sakya-trizin/http://truthaboutshugden.wordpress.com/category/past-masters/sakya-history/http://www.himalayanart.org/search/set.cfm?setID=490