A client is going to shoot footage using Canon XL1S in its 16:9 option. Will I have any problems using PE7 HDV preset? I will also be shooting using my Canon XHA1 in HDV 16:9. I know thw XL1S is standard, so I will be mixing HD 16:9 with standard 16:9, and I am ok with that.
The XL1 is a miniDV camcorder shooting standard-definition video. I would not try to mix it with HDV in an HDV project.
If you do this, you will need to scale the miniDV footage by over twice the vertical and twice the horizontal resolution in order to fit the frame -- and it's likely to look fuzzy and pixelated. You will also need to reverse the interlacing for the miniDV footage (since AVIs use lower field first resolution and MPEGs use upper field first) and you will need to continually render the miniDV footage as you work.
It's just not a good mix, and it's not likely to produce good results, IMHO.