My main cam has been a vx2100 for the past 2 years, in the summer of last year I wanted to buy a second cam and had the same worries as you, should I invest in hdv or not. because of hdv the prices of good dv cams started to drop I decided to buy a dvx100 and I haven't regret it so far.
It all depends for what you will be using it for, I"m in the wedding business and for this year f.i. I"m booked full and no client has asked for hdv. All of them had still plain, often 4:3 tv's.
Beginning next year however I will switch to one hdv cam for sure, probably will sell my vx2100 and keep the dvx100 as backup cam or for specific assignments. For next year I will be expecting more hd requests, blue ray or hd dvd will become cheaper for sure and more people will start to have a complete hd ready sets.
So for your question, if you use the camera professionally I would buy a XH A1 (Assuming you have no camera at all), if you use it just for hobby, go for the xl2. The xl2 however is still quite expensive (I think that it costs approx the same as the XH A1. But that will not last, canon will not be able to justify the high xl2 prices for a sd cam and maybe you will be better of waiting a bit longer if you want better deals. The dvx100 f.i. can allready be found several 100 euro's cheaper then last year.
You allready mentioned it and it's surely something to consider and that's the pc upgrade you need to do, that's money you will save when you get the xl2.
Several of my competitors got a hd cam about 1,5 -2 years ago (The fx1 which was very popular then) and still they had to take a sd cam with them for dark shoots because the fx1 was just not up to it. To the customer they had to deliver a downconverted sd footage so there was no advantage. Only advantage was if they sold their original minidv tape with the hd recordings so it could be transfered to blue ray in a few years.
My dream is a hvx200 with 2 large P2 cards, just like you I will have to make the right choice again next year and at the meantime I will probably still make somebody very happy with my vx2100.
