Topband: "T" Antenna VS 30m high vertical

[ik0yvv at libero.it]

Hello All,
As in each summer ideas to improve the low bands antennas are going to become real work.
Now i'm using an 18m vertical with 2 slope wires (each 10m long and with an angle of about 45° ...i know it's a little bit too much but not enough room), i tune this antenna on 160 with a coil (about 21uH 20cmx20cm) and on 80m with a vacuum capacitor ... having a "far from perfect" ground system (60 radials of various leight but most of them folded to enter in my garden of 12mx12m) this configuration really surprised me on both bands: on 160m the antennas performs really well (in 2 winter seasons give the possibilities to work all the 40 zones and i need few "hard" states to finish the WAS) and on 80m is really a killer antenna .... 
I was thinking to take down this antenna and putting a 30m high vertical without the 2 capacitive wires .... those 2 wires gave me in the past several meccanical problems even because there is a tree too close to them and during windy days it can happen that one wire get in touch with the tree.
Looking on the Low band bible by ON4UN and modelling the 30m vertical with eznec it seems that the antenna i'm using now has a better efficency of the 30m one. I'm not an antenna guru at all ... so i'd like to know your opinion. The 2 10m long wires makes the radiation resitence a little higher, but i were thinking that a 30m high vertical should have been a big improvement in both bands ( 80 and 160) ..... what do you think about ? 
I do apologize with the gurus on the reflector if the question is too easy, but before taking down this antenna and doing all the work to put a 30m vertical pole (it's not an easy work) i'd like to have your opinion too to avoid a second work in taking down the 30m vertical to put on the one i'm already using.
Thanks in advance and have a nice week-end.

Marco , IK0YVV