"...centered on the edge of the counter top, and spaced about 3' apart; will a 50W par 30 flood have enough light?"

Yes, that should make the counters quite bright. Make sure you get normal PAR flood bulbs, not spots or the tighter "narrow floods."

Thanks for the info jon1270. Will the deep cone make any difference?

Juno IC20 with deep #206 cone: When using the deep cone the lamp socket is fastened to the top of the housing and the cone shape allows the use of even short par 30 lamps so the lamp is deeply recessed. This is good for lamp concealment with high ceilings where 50 watts is enough. It might require using a narrow flood or spot to compensate for height. Yes, a small aperature opening and deeply mounted lamp will affect the beam spread.

The regular cone #216 has a socket mount at the top so you relocate the socket from the top of the housing to the trim. The cone is shaped so that a short par 30 will not fit without a socket extender. These trims work well with par 30 long neck wide floods 75W Par30L WFL. With non IC housings standard A lamps can also be used since #216 is a reflector cone. And that is also why the short Par30 will not fit because the cone is shaped to project the light from an A lamp.

A long neck par 30 is a bit shorter than a BR30 and the Par30L looks OK in these trims with 8' ceilings but I don't recommend you use this trim and R or Par lamps for higher ceilings.