Whisker Pole vs Cruising Spinnaker
If you need to buy a pole get the stongest that you can afford to be able to carry the sometimes high compressional loads that will buckle a weak pole, put a toping-lift bridle on it.
Honestly, after wrestling with an symetrical chute for 15 years while short handed or single handing a Pearson 30 and now having a much larger boat with only asymetricals... Id suggest to sell the Symetrical kite, buy an Asymetrical (or make your own .... Sailrite, etc. as spinnakers are relatively easy to make from kits). When you are single handing and just plain want to relax, using ANY pole is simply a big PITA. With an asymetrical: No more dip-pole, end-for-end, two pole gybes, no more foreguys, lazy guys, braces, topping lifts, downhauls, etc....... just 2 sheets and a tackline (and a chute scoop).
If you want to come dead down wind with an asymetrical you will still need a pole .... or sail with the rig on the lee (wing & wing) with a preventer, etc. on the boom.
In light winds, you can also take a symetrical (& without a pole) attach it to the forestay (ATN ''tacker'' is OK) and sail dead downwind while on the lee with the mainsail over trimmed - looks like hell but it works, otherwise when tacked to the forestay (just as with an asymetrical) you will be limited to broad reaching to beam reaching..... if you want a fly a kite with any stability.
Another consideration for your presnt symetrical is to fly it from a pole on one side/tack and then let the pole foreward and sail it like an asymetrical on the other tack - never disconnecting the sail from the pole and letting the symetrical loosely fly across the bow during the gybe - sheets are attached to the same clew - like with an asymetrical. Its all the damn pole manipulation that makes flying a symetrical a PITA.