reklaw - Go for it! You're set up for life as far a macro goes. I wouldn't even look through the 250 a this point. Get used to the +4 diopter 150. That's really powerful enough for 85% of macro shots, IMO. And don't feel you have to go to full zoom all the time. Start at 5-6x. You get alot of magnification right there and it will be easier to focus. Frame and zoom as you normally would. Get good with the 150 before jumping up to the 250. The depth of field is extremely shallow at 12xwith a+8 diopter lens (2-3mm), making it very difficult to focus. It takes alot of practice.
And then you have the option of stacking the two for a total of +12 diopter.:?