I hold both and I agree JS. FWIW with BILL on a PE of 7 at the arb rate the UCL option looks the best. I also think if BILL are serious about a speedy move to the Main Market then it would need to be done by about Feb 8th to qualify for the SMX in March. The next option would mean waiting until June. Whatever happens once the uncertainty is over these should re-rate, particularly with BILL. A SMX entry would lead to tracker buying (from almost nothing held as it is to the trackers buying enough stock to track a £250m or so company).
EVBG have a target of 145p (from memory) on BILL which at the current arb rate with UCL suggests they could double. Even then a PE of 14 looks reasonable value to me.