Sensible
That is a very old GPS design, about 10 years old. I think you will find that performance has moved on a long way since.
However most aviation GPS products on the UK market aren't that much younger; there is very little innovation going on for some reason.
A roof-mounted GPS antenna should always be used; the school/syndicate may not want to pay for it (£300 or so) but it will benefit everybody who uses a GPS (which is almost everybody when there is no instructor in sight
)