Received an offer from CO - join Presidents club and $50 joining fee is waived, plus get *either* 5000 regular miles *or* 1000 EQM.

now - looking at CO website it seems if I join I can use many of the lounges at LHR (including the SkyTeam one at T4) plus a bmi one at T1. Plus access to various lounges in the USA.

Questions / comments are (am silver on CO, btw)

1) Am I OK to use bmi lounges at T1 with a PC club membership, and can I use the SkyTeam lounge at T4 when flying in economy LHR-EWR on CO based purely on my PC membership (i.e. not *G or flying business?) That's what the CO website suggests, and that seems pretty decent.

2) 5000 miles for approx $400 is good value compared to the rough cost of flying cheap LHR-EWR-PIT (approx minimum $600 for ~4k miles) - right?

3) Assuming 5-6 transatlantic runs a year, that's ~12 uses of lounges that's about $30/use - about the same as paying for access to Hollideck at LHR. Plus other occasional bmi flights (2-3 RT/year) it starts looking like decent-ish value.

4) Flying on UA next week, if I joined PC what lounge could I / should I use at T1?

My gut feeling is that it's worth it - lounges are nice when things are going smoothly, but priceless when the delays kick in. As long as I can use the whole variety of lounges at LHR on a economy ticket.

Or am I missing some catch?