Well, I haven't seen the LED Par38's myself yet. I get some karaoke gigs here and there. Mainly for weddings.
I started with regular Par38's because they were cheap, and with a dimmer pack and gels, I could get any color I wanted. Small stages didn't take a whole lot to get the job done. Well, 32 incandescent Par38's later and I'm not happy with these, despite them being ADJ fixtures and working 100% perfectly. Why do I hate them? Too little light, or rather too much diffusion and not enough cut through/projection, but that's part of the nature of Par38s.
I would suspect the LED Par38s to offer the following advantages, which make them a decent deal. First off, the LED's are DMX, and if like the 64 LED Pros(which I have 8 of), give you tons of features and control. No dimmer pack, but maybe more overall weight. However, your power draw is so small, so you can throw more lights on a stage and not worry about a breaker.
Now, with my 64 LED Pros, I'm learning I really need to raise these up more than I have been. Once you get enough distance between the lights and the stage/zone, they work fantastic as it is a more defined beam, despite being a more wash-style fixture. With the LEDs at the front, I was expecting more wash and less beam, but that's not the case. It's really comparible to a regular Par64.
With the LED Par 38 and the LED par64, you do get what you pay for. By that, cramming in DMX-512 brains into the fixture, 7-channels of DMX control, runs cool and is low draw, you spend a decent amount of money and get a really good fixture. So, the Par38, being a smaller fixture, you're gonna get less light. But if they behave like reglar Par38's, you get a wider wash for shorter throw, which works fantastic on short stages/small stages and lower stand heights.
You definately need more height/distance for Par64's, period, LED or not. It's the nature of the fixture. Maybe a Par56 might be better? LED OK too.
Or maybe something like the Punch Pro and just do a general stage wash? Maybe a Mega panel? I think I'm going to be adding a MegaBar or MegaPixel for foot lighting. I'd make more suggestions buy my ISP is such total crap today I can barely get anything done.
Pick a budget and try to stay within it. But, if you go Par64 LED solutions, please choose the LED PRO versions, it is a MUCH better option. Par38s have less throw, while 64's need some room to throw. This is something to seriously take into consideration.
At my next show, I have a large stage and I can NOT use trusses because it's a movie event. The 8 64 LED Pros will give me some medium projection into the stage, 4/tree, 1 tree/side of stage. My Chauvet Intimidator Color units will give me deeper projection, but I won't need as much back there so having only 4(2/side), that works out. I'll use a tree of 8 Par38's on each side of the stage as well to get some wash for the edges of the stage, and use my Color Fusions for additional wash. I'll use my 2 spots for more attention and if I need to do more fill, I'll use my Chauvet Q-Spots. That's going to make me burn 3 circuits for lights. If I had the money and went all LED, I could run all that off of one circuit. That's a great argument for going LED right there.
Think what works. What are your stands and heights, ceiling heights, stages, distance, things of that nature.
See what Jingles has to say on this issue as well. I'm a sound guy.