I had some Summit Funds until recently but I cashed them in because I needed the money for something else.
I had one mutual fund which was gross roll up and growth was taxed at 41% exit tax on encashment. The other was an investment fund which was subject to deemed disposal every 8 years and subsequent exit tax on encashment as necessary. Either way all taxes were taken care of within the funds and/or at encashment time.
As far as I recall the management changes weren't competitive - c. 1.2% and 1.5% I think. There are much more competitive annual management charges available these days on managed/index tracking funds. And, of course, direct equity investments are much more attractive from a tax point of view (CGT @ 33%, ability to offset previously incurred losses, annual exemption of €1,270).
Can't really say if the new servicing agent is a reason to cash in but there may be other good reasons to do so.