They have also spent a first full season in their new home of Scotstoun and Gregor Townsend's men will be expected to challenge for honours again next season.
And Lineen, who spent nine years at the club before leaving to join the SRU last summer, revealed he's envious of the talent at Townsend's disposal.
"I wouldn't be human if I didn't feel a touch of envy seeing what we built up being added to with the likes of Maitland, Stuart Hogg coming through, DTH [van der Merwe], and great young Scots, but life is full of challenges," he told the Scotsman.
"I loved my time coaching, but nine years at one club is a long time. When you're working hands-on as a head coach with a team you don't actually realise how much of a bubble you're in.
"It is very, very intense, and you, and your family, make a lot of sacrifices. You have to be very selfish and focused on the team and you need massive support from your family."
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