We describe an experimental study of two distinct microchannel plate (MCP) detector configurations with extended dynamic range. First, we report on measurements made with single MCPs of very low resistance (≤500 kΩ) bonded to a Peltier cooler. Stable, reproducible operation for a rear-cooled MCP with 10 μm diameter channels of length-to-diameter ratio 60:1 was achieved for biases up to 1320 V. At this point, the MCP strip current was 5.1 mA and the rate of internal heat generation, 0.78 W cm -2. A maximum count rate of 10 8 cm -2 s -1, limited by the available intensity of UV illumination, was observed, coupled to a dark noise count rate of less than 1 cm -2 s -1. Second, we describe a substantial (up to 20-fold) improvement in count rate capability for two-stage MCP multipliers incorporating plates with gold, rather than nichrome, electrodes. We also present, in support of the experimental study, a thermal model of bonded, conductively-cooled MCPs which we use to determine critical parameters for stable detector operation.