Canon redesigned the flash system to accept up to 250 volts, so you are safe with Cameras released after the 10D and almost all flash units. I'd still stick to those 200v or less, or use the Wein unit.
Here is the forum thread that Canon Tech Guru Chuck Westfall confirms that all newer Digital rebels have a 250v rating.
Chuck Westfall, Director/Media & Customer Relationship, Canon USA, advises as follows regarding the flash sync circuit of the EOS Digital Rebel XT (EOS 350D):
The EOS Digital Rebel XT uses a modified version of the EOS 20D's shutter unit. Consequently, acceptable trigger circuit voltage for both cameras is the same, i.e., 250 volts. Except for the original Digital Rebel, all current EOS digital SLRs (i.e., EOS-1Ds Mark II, EOS-1D Mark II, EOS 20D and EOS Digital Rebel XT) generate their X-sync signals electronically rather than mechanically. This is why they have higher acceptable trigger circuit voltage ratings than earlier models like the D30, D60, 10D and original Digital Rebel. These older models cannot be modified to achieve a higher trigger circuit voltage rating, since such a modification would require a different shutter mechanism as well as a complete redesign of the supporting circuitry.
Read the entire thread here. Scroll down to see Chucks confirmation of this.http://www.prophotohome.com/forum/canon-eos-digital-slr-1-6x-sensors/53600-digital-rebel-xt-350d-flash-sync-voltage-rating.html