Really my only issue is the fact we're getting a much smaller science center - with that said, a lot of the science center was open space / greenery / outdoor sections - so purely from an exhibit space perspective it's not clear to me how much different it really is ? Side note, I loved the science center growing up, I suspect many did, and I thought they did a decent job keeping it up to date until maybe ~ 2010 (it really was one of the premier North American science centers in the 1990s+) I recall I believe the telus expansion - but since then ... with the lack of investment, I find it's turned into a glorified daycare - as the exhibits are so old, in bad shape, and out of date (from a science and technology perspective).
Another thought - so the science center of course had the imax theater - is cinesphere going to be used in such a capacity as that would be great ? Do you know what would have been a dream come true, no clue if this is really feasible, but turn the cinesphere into a world class planetarium (that can still show movies as well).
I do not think the "spa" is necessarily a bad fit, assuming there is enough variety (i.e. for kids and adults) the fact that it and the science center are all year venus that's a huge win for the area.