A little late to the party. I love flaps only approaches. My experience is highly limited to one glider, the Neidrauer NG-1, a modified BG-12/16. It has large chord large span flaps. I've never seen an HP-14 so don't know how it compares in size/effectiveness but when I did my first flights in the glider the problem was coming in short not going long. Full flaps and 55-60 mph gives a measured glide angle of 5:1 or so. How can you not like that? I do think it is important for would-be flap only pilots to read through discussions such as this one. Having some airplane time can't hurt, especially in the large flap Cessnas from days gone by. Shooting an hour of power off landings in an old 40 deg flap 150 will help you get the idea of how flaps affect the glide angle and sight picture with the comfort of a CFI next to you.

I've never seen a problem when I modulate flaps in the pattern in practically the same manner as i modulate airbrakes. However you have to remember that with each flap change there must be a corresponding pitch attitude change. Go from full to none and keep the nose pointed down and that is exactly where you will go.