My experience with SE2:
A well designed bit of kit, sees ADSB targets well on Skydemon and is good source of GPS to non-GPS tablets.
BUT only a small fraction of small aircraft currently transmit ADSB. This means one sees the grown up aircraft going into the big airfields but not the small ones that one may bump into.
I expect we will all be made to have ADSB soon (cue another expensive transponder change just after we have all installed mode S) so this will not be a problem (if you see what I mean!).
The other solutions probably see more today but IMHO are a dead end and will be obsolete when ADSB gathers steam.