Just sharing my experience, i'm one of the residents affected by SERS in 2016 (new flats still under construction, pending completion by Q3 2022).

We were offered two separate sites - Clementi Peaks (Site A) and West Coast Parkview (Site B). Each site had about 600 units each. Similar to the Ang Mo Kio project, most of the residents in my affected estate are all seniors in their 50s and retired elderly. And back then there were already a fair amount of noise on how unaffordable the Clementi site was, since that is located nearer to the MRT. IIRC we were also offered around $450K for our 4-room. The Clementi flats cost at least $500K to $550K at the bare minimum if you are looking into a one-for-one 95sqm replacement at a similar storey.

Ended up the overwhelmingly majority (70% of the affected residents) took the West Coast site instead because the flats there were considerably cheaper in price (between $380K to $450K).

HDB knows this, and this is why you find that SERS replacement sites always offer a smaller 4-room option at 83-86sqm in addition to the standard 90-95sqm. The former is considerably cheaper by at least $70K. Basically they're saying, if you can't afford the one-for-one replacement, downsize your flat. Is it really fair? I think this is open to interpretation.

SERS is theoretically a good deal if you are still young and working, since you are giving a guaranteed new 99-year lease. But if you are a retiree, especially one in which you need to pledge your housing to meet your CPF minimum sum? Not so much. I don't think anyone in their 50s and 60s really have the energy to move house anymore.